Merge pull request #125 from dsanders11/master

Fix for Submission.publish_date default value
closes #103 add support for Django 1.7
refs #103 move south migrations to south_migrations folder, add new migration, replace logic in defaults with save method to prevent lambda serialisation error in makemigrations
Merge pull request #120 from ctxis/master

closes #103 add support for Django 1.7