Security fixes mean both a new Django 1.6 and Django 1.7 version.

I missed that RC2 was released three days ago. I now follow
@djangoproject so that doesn't happen again.
The release candidate is a much saner target to test against, so let's
do that.

It now:

- Restores the previous versions of Django and South
- Uses a bash array to reduce duplication

(Took the bait from 722c058e5a)

Django 1.7 still suffers from a range of migration problems. This one
caused migrations to be created infinitely:
https://code.djangoproject.com/ticket/23014

A commit prior to that change, but containing the fix for #23041, fixes
the issue for now.

This crude and destructive script helps create migrations for both South
and Django's native migrations framework. I'm happy to leave plenty of
room for improvement so that the King of Bash (aka @codeinthehole) can
do his thing.

This commit also enforces South 1.0. It's a backwards compatible release
which explicitly is meant to help the migration; it makes both our and
our users life's easier. Notably, it first looks for a south_migrations
directory before falling back to the migrations directory in an app.
That nicely avoids any conflicts between migration files between the two
migration frameworks.