Celery-once

-----
2019-08-21

Behind the scenes, changed how key's are generated from task function and arguments.
No longer uses ``inspect.getcallargs`` (deprecrated) and is stored on ``__init__``.
Should fix issues if tasks are wrapped by other libraries (i.e. sentry-python).

-----
2019-05-13

Fixed an issue where large/long arguments could cause ``OSError Filename too long`` with the file backend (see 96).
Keys generated for file backend, are now hashed and limited to 50 characters in length.
*Due to this, it is not backwards compatible with existing keys from the file backend, so any pending locks from previous version will be ignored.*
The Redis backend is unchanged, and thus fully compatible.

Credit for fix to xuhcc.

-----
2019-05-13

- Add support for ``rediss``. Thanks gustavoalmeida

-----
2019-05-08

- Fix an issue with the ``File`` backend (89) to close file after creation, else unclosed file descriptors eventually lead to an "Too many open files" error. Thanks xuhcc.

-----
2019-02-25

- Added ``File`` backend (84). Credit and thanks to xuhcc.

-----
2019-02-25

- Fixed an issue when using ``autoretry_for`` with a task. (74, 75). Thanks pkariz.