Django-qsessions

I think everything is OK for releasing `1.0.0` since django-qsessions is working fine in production for long time.

- Drop support for Django 1.10.
- Drop support for Python 3.5, since its end of life is near. Plus, maxminddb doesn't support 3.5 anymore.
- Add Django 3.1 to support matrix.

- Drop support for Python 2.
- Use `ipware.get_client_ip` instead of `ipware.ip.get_real_ip` (which is removed since `django-ipware==3.0.0`)
- Format source code using [black](https://github.com/psf/black)

Thanks [sevdog](https://github.com/sevdog)

- Updated `download_geoip_db` management command to use new Maxmind download URLs, and provide license key.

Thanks [akx](https://github.com/akx)

- Added Django 3.0 to support matrix.
- Removed Python 3.4 from support matrix.

- Added `qsessions.backends.db` session backend.

Thanks [willstott101](https://github.com/willstott101)

- Added support for Django 2.2.

Thanks [akx](https://github.com/akx)