Basic Django REST Framework installation

Add the `rest_framework` app, add `djangorestframework` to
`requirements.txt`, and set up the urls for the Django REST Admin views.
Modify settings and url to handle api.
Views to list and get Users.

Go to `localhost/users/` to list all Users.
Go to `localhost/users/id` to get a specific User.
If you request HTML from those pages it'll spit out a nice HTML view for
listing and editing Users. If the frontend JS requests JSON it'll spit
out a JSON representation of the Users/User.
Add .travis.yml
merging pull request