Delete CaseInsensitiveCharField once we can use CITextField

[sjamaan]

Some upcoming version of Django will have a CITextField. Then we can get rid of our CaseInsensitiveCharField.

[sjamaan]

Oh my, looky here

[irfinnew]

\o\
/o/
\o/

[irfinnew]

This is actually part of the now-released Django 1.11.

See https://docs.djangoproject.com/en/1.11/releases/1.11/#django-contrib-postgres

[sjamaan]

I've added a deprecation warning to point people in the right direction.

I'll leave this ticket open until there is no longer any project that actually uses it. We'll also need to consider what to do with any migrations that might possibly be using it (it would be easy to just rewrite them to use CharField or something; there should always be a later migration to use CITextField, so that's actually safe, but still annoying).

NOTE: I had to add psycopg2 to the dependencies to make this work, because otherwise we can't even import CITextField. We should really consider dropping all support for sqlite, as we don't even use it in any of our projects, and it might start hampering our ability to make full use of all Postgres goodness offered by Django (for example, now we can't add a test for the case insensitive fields).