Update Django (1.6.5 -> 1.7c1)

We decided to use Django 1.7 and Python 3.4.

Furthermore, south with SQLite doesn't work with Python 3. Thus we're
upgrading now, which allows us to use SQLite on developer machines.
Use SQLite in development setups
No need to install pysqlite package

sqlite3 is in the standard library, so we don't need an external
package.
Merge branch 'feature-django1.7-sqlite' of https://github.com/nidico/policycompass-services into nidico-feature-django1.7-sqlite
Merge branch 'nidico-feature-django1.7-sqlite'