Implemented #76, minus the tests

New requirements, so please run ```pip install -r requirements.txt```

Also new fields in the Author model, so nuke the DB.

It's not ideal.  Ideally we wouldn't be saving these things as Post objects, but our
templates rely on them being Post objects.  Or, we keep saving these things, in the
rationale that we are able to not hammer GitHub as often (I have this implemented to
atone for my bad, bad ideas).

If you guys don't want to bump into the 60 requests per hour limit, I suggest registering
for an application token: https://github.com/settings/applications/new

Once you've done that, in settings.py, make two new key-value pairs:
```
GITHUB_CLIENT_ID = 'CLIENT_ID_GOES_HERE'
GITHUB_CLIENT_SECRET = 'CLIENT_SECRET_GOES_HERE'
```

After that, you'll have 5000 requests per hour!
Merge branch 'master' of https://github.com/awwong1/CMPUT410-Project