Release of version 2.2.0 (#83)

* migration to pyproject.toml

* fixing workflow

* adding optional dependencies for tests

* added python parametrization for CI pytest

* new release

Bumped gunicorn version to one supporting python3.7

Greenlet fix

Pinned greenlet version, bumped filetracker version.

Bump version to 2.1.3 (#74)


 Use open from io module to load the description, so that it's compatible with both python2 and python3

 Made naming rules more lax and migration script more stable. (#70)

Bumped version to 2.1.1. (#69)

Bumped version to 2.1 (#66)

Changed flock to active-waiting and increased the timeout. (#60)

* Changed flock to active-waiting and increased the timeout.

* Added EWOULDBLOCK just to be sure.

* Fixed tests?

* Changed waiting for lock logic.

Fixed gunicorn and gevent dependency versions. (#64)

This should fix tests, which suddenly broke because of new gevent
release.

Fixed travis deployment config. (#63)