Upgrade south and fix a bug in the commit message lint script

 Things done to upgrade south:
    1. Update South to version 1.0.1 in requirements.txt using peep
    2. Rename all 'migrations' directories to 'south_migrations'
    3. Build a new VM and verify that the migrations apply.
    4. Run the unit tests and verify nothing is broken.
    
South package present in vendor/packages has not been updated

Fixed a bug in the commit message lint script by making it ignore the commented lines in the commit message.