Huey

* Add backwards-compatibility to queue serialization protocol so that 1.6
consumers can continue to work with tasks enqueued by huey versions 1.5 and
lower.

[View commits](https://github.com/coleifer/huey/compare/1.6.0...1.6.1)

* Support for [task pipelining](http://huey.readthedocs.io/en/latest/getting-started.html#task-pipelines) and task function partials
(which is not compatible with 1.5's task serialization format see note below).
* Support for triggering task retries using `RetryTask` exception.
* Support for task locking, restricting concurrency of a given task.
* Getting result of task that failed with an exception results in a `TaskException` being raised.
* Updated health check to ensure the task scheduler is always running.
* Refactor implementation of `task()` and `periodic_task()` decorators, which should have the added benefit of making them easier to extend.
* Refactored result-store APIs to simplify serialization / deserialization logic.
* Fixed bug in serialization of task exceptions.
* Added simple client/server implementation for testing locally. [Blog post on the subject](http://charlesleifer.com/blog/building-a-simple-redis-server-with-python/).

Task serialization format

In v1.6.0, the serialization format of tasks has changed to accomodate an extra
piece of metadata. As a result, tasks enqueued with huey versions previous to
1.6 will not be able to be consumed by the 1.6 consumer.

At present there is a workaround available in 1.6.1, but it will be removed
when 1.7.0 is released later.

[View commits](https://github.com/coleifer/huey/compare/1.5.6...1.6.0)

* Allow arbitrary settings to be specified in ``task()`` decorators.
* New task name format includes function module as part of task name.
* Fix for operating systems that do not implement SIGHUP.
* Fix bug in `contrib.minimal` task scheduler timing.

[View commits](https://github.com/coleifer/huey/compare/1.5.5...1.5.6)

* Implemented [pre-execute](http://huey.readthedocs.io/en/latest/api.html#Huey.register_pre_execute)
and [post-execute](http://huey.readthedocs.io/en/latest/api.html#Huey.register_pre_execute)
hooks.
* Implemented task cancellation mechanism as part of pre-execute hooks.

[View commits](https://github.com/coleifer/huey/compare/1.5.4...1.5.5)

* Implemented atomic "set if not exists" for Redis and SQLite, which is used by
the locking APIs.

[View commits](https://github.com/coleifer/huey/compare/1.5.3...1.5.4)

* Includes addition of `TaskLock` and `Huey.lock_task()` helpers.
* Extend `Huey` API to add method for creating the consumer.

[View commits](https://github.com/coleifer/huey/compare/1.5.2...1.5.3)