Removing get_default_session() to make new Migrations work

Add support for vagrant-cachier to reduce VM rebuilding times
Replace South Migrations with Django 1.7 Migrations and adjust install/deploy scripts to work.
Fixing unit tests due to removed RWValidatedFileField. AttributeError: 'set' object has no attribute 'items'
Updating roundware.wsgi with Django 1.7 syntax and setting test runner.

Run migrate by the correct user during install/deploy