django-filter 1.0 compatibility

[nemesifier]

The current version of drf-gis is not compatible with django-filter 1.0 yet.

I am not going to work on this issue unless I will need it for one of my projects, therefore, for those who do use this kind of feature, I invite you to contirbute.

[blueyed]

What exactly does not work?
I assume it will show up in #121 due to a new build?

[nemesifier]

@blueyed I am not following you: I was talking about django-filter 1.0, not django 1.10

[blueyed]

I was talking about django-filter 1.0

Sure, but that gets used in Travis, isn't it?

I was wondering, since it works in our project - so it might be more an issue with the tests than the app itself?!

[nemesifier]

@blueyed, the previous recent builds were failing. I fixed the builds by pinning specific versions of drf and django-filters (see requirements.txt and requirements-tests.txt respectively).
django-filter 1.0 breaks compatibility with previous versions so the code needs to be adjusted while maintaining backward compatibility, more information available at https://django-filter.readthedocs.io/en/develop/guide/migration.html.