feature/load-initial-data

This PR adds the ability to import HAA flashcards into the application database. 

To do the importing, you can follow these simple steps:

1. After pulling changes from github, cd to HarvardCards in the command line terminal.
2. Execute python initial_data.py. This will create the json files as per the format of django's models. There will be multiple files (6 in total) because of the way the application is set up (intermediate model classes etc).
3. Then execute python load_initial_data.py. This will load the json files created in step 2. You have to load the files in a certain order (by running python manage.py loaddata filename), so I thought it will be a good idea to create a script for that. 

After that, you can run the server on your machine and go to the admin site to view the cards etc.

Note: this PR was pulled out of the dev branch and made into a PR in order to facilitate a review of the changes being made.