Southization of LFS

This pull request is intended to convert latest version of LFS to south. It doesn't affect older versions of LFS. The pull request contains:

1. initial migrations for all LFS apps that have any models defined
2. enhanced lfs_migrate script - after migrating to latest version the command: bin/django migrate --all --fake 0001 and then bin/django migrate is called. 

The above means that:

1. a new user who is going to install lfs will have to call bin/django migrate command
2. an existing user who is going to migrate his shop from older to the latest version will have to call bin/django lfs_migrate command
3. all further models changes should have migrations generated for them, and users migrating to newer versions will only have to call bin/django migrate
4. 'south' should be added to INSTALLED_APPS in project's settings

Other:
Pulling these changes will make LFS south compliant and will make it's further development easier.