Kiwi-cache

Added

- better docstring for `BaseKiwiCache` and `KiwiCache`

Changed

- fix initial value of `expires_at` attribute of `KiwiCache`
- fix `KiwiCache` data prolong if local `_data` is filled
- change `instances` array to dict

Added

- Black check for gitlab CI

Changed

- Remove using arrow
- Remove using attrs for class attributes
- Format docs by Black project

- Generalize KiwiCache and use attrs
- Format of code by Black project

Changed

- Add tests to check functionality of ttl
- Validation for initial parameters
- Fix missing connection to Redis in SQLAlchemyResource

Changed

- Rename DBTableResource to SQLAlchemyResource

Added

- Python 2.7 compatibility
- README, Changelog, Contributing
- SQLAlchemyResource
- Attempt limit of failed load_from_source calls
- Integration tests
- logging
- Instrumentation with datadog.DogStatsd

Fixed

- Data in redis actually expires. Specified by `cache_ttl`, defaults to 10 \* `reload_ttl`.