Django -> 1.7c2

In preparation for setting up a table for user data for the configurable
dashboard, I thought it would be a good opportunity to try Django 1.7's
built-in migrations.

I've followed the instructions here:
https://docs.djangoproject.com/en/dev/topics/migrations/#upgrading-from-south
- Deleted south migrations
- Ran ./manage.py makemigrations

There were also some changes necessary to the casper integration tests.
They seemed to be in bad shape -- maybe they weren't getting run
correctly? I've corrected the window size, and fixed some tests here.