Consider removing Django integration

[Colin Watson]

lazr.restful has some Django integration code. I don't know who's using this, if anyone. https://bugs.launchpad.net/lazr.restful/+bug/640132 indicates that canonical-identity-provider (SSO) was using it at one point, but it no longer does. Our tests for this integration code are artificial: they install fake modules and don't install Django itself for testing, so it's quite possible that this no longer works.

If anyone is still using this, then we should fix the tests to ensure that lazr.restful actually works with Django proper. If not, we should probably remove this unloved code in lazr.restful 2.0.