Django 2.1 support

[barseghyanartur]

Any idea on when would Django 2.1 be supported?

[pasevin]

Yeah, need this badly. Is there any news?

[okke-formsma]

has anyone found an alternative with django2 support?

[Natureshadow]

I could not find any incompatibilities with Django 3.

[nikolas]

I use celery-haystack with Django 2.2 on this project, and haven't seen an issue: https://github.com/ccnmtl/footprints

Current Django versions should definitely be added to the test matrix, though. I made a pull request to at least add Django 2.2.x here: #79