Ddtrace

**Bug fixes**
- [opentracer] Activate span context on extract (606, 608)
- [opentracer] Fix "does not provide the extra opentracing" (611, 616)

**Improvements**
- [docs] Clarify debug mode (610)
- [docs] Fix docstring for `Tracer.set_tags` (612 -- thanks goodspark)
- [docs] Add priority sampling to ddtrace-run usage (621)
- [circleci] Imrpve python docs deployment strategy (615)
- [tests] Refactor tox.ini file (609)
- [tests] Improve performance of tests execution (605)

Read the [full changeset](https://github.com/DataDog/dd-trace-py/compare/v0.14.0...v0.14.1) and the [release milestone](https://github.com/DataDog/dd-trace-py/milestone/27?closed=1).
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**OpenTracing**

In this release we are happy to introduce the beta for the long-awaited OpenTracing compatible API layer for `ddtrace`!

Support for `opentracing>=2.0.0` is provided in this release. Namely, the following are supported:

- `start_span`/`start_active_span`
- `inject` and `extract` functionality
- `baggage`, through `set_baggage_item` and `get_baggage_item`
- compatible tags from the [OpenTracing specification](https://github.com/opentracing/specification/blob/b193756f1fe646b79ef4f901bed92c0e72845440/semantic_conventions.md#standard-span-tags-and-log-fields)
- scope manager support
- seamless integration with the Datadog tracer when using `ddtrace-run`

For setup information and usage see [our docs for the Datadog OpenTracing tracer](http://pypi.datadoghq.com/trace/docs/installation_quickstart.html#opentracing).


**CI Improvements**

Also included in this release are some optimizations to our CI which should get things running a bit quicker.

Thanks labbati!



Read the [full changeset](https://github.com/DataDog/dd-trace-py/compare/v0.13.1...v0.14.0) and the [release milestone](https://github.com/DataDog/dd-trace-py/milestone/20?closed=1).
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**Bug fixes**

* [core] remove the root logger configuration within the library (556)

Read the [full changeset](https://github.com/DataDog/dd-trace-py/compare/v0.13.0...v0.13.1) and the [release milestone](https://github.com/DataDog/dd-trace-py/milestone/24?closed=1).
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**New integrations**
- [`pymemcache`](https://github.com/pinterest/pymemcache) integration (#511)

**Celery integration**

Due to some limitations with our Celery integration, we changed our instrumentation to a [signals based approach](http://docs.celeryproject.org/en/latest/userguide/signals.html). We also started using import hooks to instrument Celery, so that enabling the instrumentation doesn't trigger a `celery` import.

- Signals implementation: 530
- Moving to import hooks: 534
- Resolved issues: 357, 493, 495, 495, 510, 370

**Breaking changes**
Using the signal based approach increase the stability of our instrumentation, but it limits what is currently traced. This is a list of changes that are considered breaking changes in the behavior and not in the API, so no changes are needed in your code unless you want a different behavior:
- By default all tasks will be traced if they use the Celery signals API, so tasks invoked with methods like `apply()`, `apply_async()` and `delay()` will be traced but tasks invoked with `run()` will **not** be traced.
- `patch_task()` is deprecated; if it's used, all tasks will be instrumented

**Bug fixes**
- [core] check if bootstrap dir is in path before removal (516 -- thanks beezz!)
- [core] have hostname default to `DATADOG_TRACE_AGENT_HOSTNAME` environment variable if available (509, 524 -- thanks hfern!)
- [core] add WSGI-style http headers support to HTTP propagator (456, 522)
- [core] Enable buffering on `getresponse` (464, 527)
- [core] configure the root logger (536)
- [aiopg] set the `app_type` during initialization (492, 507)
- [boto] default to `None` if no region (525, 526)
- [flask] avoid double instrumentation when `TraceMiddleware` is used (538)
- [pymongo] fix multiple host kwargs (535)
- [tornado] make settings object accessible during configuration (499, 498 -- thanks kave!)

**Improvements**
- [core/helpers] add a shortcut to retrieve Trace correlation identifiers (488)

Read the [full changeset](https://github.com/DataDog/dd-trace-py/compare/v0.12.1...v0.13.0) and the [release milestone](https://github.com/DataDog/dd-trace-py/milestone/21?closed=1).
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**Bugfixes**

* [celery] add support for celery v1 tasks (old-style tasks) (465, 423)
* [celery] `ddtrace-run` broke third-party script support; now it handles correctly the `argv` params (469, 423)
* [celery] patch `TaskRegistry` to support old-style task with `ddtrace-run` (484)
* [django] update error handling if another middleware has handled the exception already (418, 462)
* [django] `DatabaseWrapper` loaded in right thread, after removing `setting_changed` signal from the `DatadogSettings` (481, 435)
* [django/celery] add `shared_task` decorator wrapper to trace properly Celery tasks (486, 451)
* [django/docs] notes about Debug Mode, and debugging (476 -- thanks ndkv!)
* [gevent] pass `sampling_priority` field when Distributed Tracing is enabled (457)
* [mysqlb] add missing services info when they're flushed (468, 428)
* [psycopg2] properly patch the driver when `quote_ident` typing is used (477, 474, 383)
* [pylons] ensure the middleware code is Python 3 compatible to avoid crashes on import (475, 472)
* [requests] add missing services info when they're flushed (471, 428)

Read the [full changeset](https://github.com/DataDog/dd-trace-py/compare/v0.12.0...v0.12.1) and the [release milestone](https://github.com/DataDog/dd-trace-py/milestone/19?closed=1).
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**New integrations**
* [boto] Botocore and boto instrumentation is enabled by default using `patch_all()` (319)
* [futures] provide context propagation for `concurrent` module (429, [docs](http://pypi.datadoghq.com/trace/docs/#module-ddtrace.contrib.futures))
* [mysql] add `pymysql` support (296, [docs](http://pypi.datadoghq.com/trace/docs/#mysql) -- thanks wklken)

**Improvements**
* [core] introducing a low-level API to define configurations for each integration. This API is used only by the `requests` module and will be implemented in other integrations in newer releases (445, 443, 450, 454, 441)
* [celery] split the service name in `celery-producer` and `celery-worker` for better stats (432)
* [falcon] add distributed tracing (437)
* [requests] provide a default service name for the request `Span` (433)
* [requests] add `split_by_domain ` config to split service name by domain (434)
* [tornado] better compatibility using `futures` instrumentation (431)

**Bugfixes**
* [core] ensure `sitecustomize.py` is imported when `ddtrace-run` wrapper is used (458)
* [flask] use `ddtrace` logger instead of Flask to avoid having a custom log filter (447, 455)

**Breaking changes**
* [celery] the name of the service is now split in two different services: `celery-producer` and `celery-worker`. After the upgrade, you'll stop sending data to what was the default service name (`celery`). You should check the new services instead because you'll see a drop. Previously reported traces in the `celery` service, are still available if you move back the time selector.

Read the [full changeset](https://github.com/DataDog/dd-trace-py/compare/v0.11.1...v0.12.0) and the [release milestone](https://github.com/DataDog/dd-trace-py/milestone/17?closed=1).
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