Added alisases to manage.py

This commit adds two shell aliases:
 - dj - Runs the manage.py script. This works anywhere inside the vagrant box and will always find manage.py (the alias uses the absolute path). Handy if you want to get to a django shell and you're in another directory. Use it like: "dj shell", "dj migrate", etc. Plus, its nicer than wriiting "python manage.py" or "./manage.py".
 - djrun - Runs "dj runserver 0.0.0.0:8000". Much nicer than typing this out manually.