refactor: Custom User model, part 1.

Rename core.models.User, which aliases
django.contrib.auth.models.User, to AuthUser in
order to make way for a proper User class.
refactor: Custom User model, part 2.

Add pykeg.core.models.User, a copy of auth.User.
refactor: Custom User model, part 3.

Update foreign keys to point to new User table.
refactor: Custom User model, part 4.

Revert references to AuthUser back to User.
refactor: Custom User model, part 5.

Remove all use of `get_profile()` and migrate mugshots
to core.User.
refactor: Custom User model, part 6: the finale!

Delete UserProfile.
refactor: Beverage support, part 1.

Adds the Beverage models.

Part of issue #157.
refactor: Beverage support, part 2.

Redirect Keg.type to new Beverage table.  Previous migration
duplicated all beer types, perserving row IDs.
refactor: Beverage support, part 3.

Update the app to use {Beverage, BeverageProducer} instead of
{BeerType, BeerStyle, Brewer}.
refactor: Custom User model: update registration support.

django-registration 1.0's built-in UserProfile is hardcoded
to auth.User, making it impossible to reuse.  Clone the
View and Form classes, using an "aware" clone of UserProfile
(KegbotUserProfile).

Rename web.registration to web.kbregistrartion due to
Django stupidly using relative app names (causing a
conflict in syncdb/migrate between registration and
pykeg.web.registration).

This change should have been included in the earlier
7-part refactor, oh well.
Update changelog.