Adds a bit of settings management + migrations (major change)

This does a couple things:

* Add slightly better settings management (there are now separate files for production and development). 
* Start using Django 1.7 migrations for foia_hub. 

I would appreciate comments and thoughts from @konklone @jackiekazil and @cmc333333 

Here are instructions: 

For settings, you'll need to add a local_settings.py file in your settings directory that contains SECRET_KEY and DATABASE_SETTINGS. I've added this file to .gitignore, so you can't commit it to the repository. 

Now that we have migrations, your lives will be easier if you: 

1. Delete and re-create your database. 
2. Run python manage.py syncdb (this should run the migration and prompt you to create an admin user). 

I have not anticipated all the issues you might run into, so if you do (and resolve them) let me know.