Apache-skywalking

- New plugins
- Pyramid Plugin (102)
- AioHttp Plugin (101)
- Sanic Plugin (91)

- API and enhancements
- `trace` decorator supports `async` functions
- Supports async task context
- Optimized path trace ignore
- Moved exception check to `Span.__exit__`
- Moved Method & Url tags before requests

- Fixes:
- `BaseExceptions` not recorded as errors
- Allow pending data to send before exit
- `sw_flask` general exceptions handled
- Make `skywalking` logging Non-global

- Chores and tests
- Make tests really run on specified Python version
- Deprecate 3.5 as it's EOL

- Feature: Support Kafka reporter protocol (74)
- BugFix: Move generated packages into `skywalking` namespace to avoid conflicts (72)
- BugFix: Agent cannot reconnect after server is down (79)
- Test: Mitigate unsafe yaml loading (76)

- New plugins
- Urllib3 Plugin (69)
- Elasticsearch Plugin (64)
- PyMongo Plugin (60)
- Rabbitmq Plugin (53)
- Make plugin compatible with Django (52)

- API
- Add process propagation (67)
- Add tags to decorators (65)
- Add Check version of packages when install plugins (63)
- Add thread propagation (62)
- Add trace ignore (59)
- Support snapshot context (56)
- Support correlation context (55)

- Chores and tests
- Test: run multiple versions of supported libraries (66)
- Chore: add pull request template for plugin (61)
- Chore: add dev doc and reorganize the structure (58)
- Test: update test health check (57)
- Chore: add make goal to package release tar ball (54)

- New plugins
- Kafka Plugin (50)
- Tornado Plugin (48)
- Redis Plugin (44)
- Django Plugin (37)
- PyMsql Plugin (35)
- Flask plugin (31)

- API
- Add ignore_suffix Config (40)
- Add missing `log` method and simplify test codes (34)
- Add content equality of SegmentRef (30)
- Validate carrier before using it (29)

- Chores and tests
- Test: print the diff list when validation failed (46)
- Created venv builders for linux/windows and req flashers + use documentation (38)

- API: agent core APIs, check [the APIs and the examples](https://github.com/apache/skywalking-python/blob/3892cab9d5d2c03107cfb2b1c59a6c77c5c3cc35/README.md#api)
- Plugin: built-in libraries `http`, `urllib.request` and third-party library `requests` are supported.
- Test: agent test framework is setup, and the corresponding tests of aforementioned plugins are also added.