Character/models.py fixes

Various changes which allows the most recent commit to be run through Django without crashing spectacularly including but not limited to:
    1. Fixing various choices to be valid tuples.
    2. Importing User from django.contrib.auth.models.
    3. Using strings for classnames where appropriate.
    4. Removing all instance of the 'choice' named parameter in favor of the correct 'choices'