Remove obsolete kb_setup tool.
Create new table, PourPicture, for storing pour-picture metadata.

'Picture' will drop these fields in the next migration, simplifying its
relationships (right now a bidirectional relationship exists indirectly
between Picture and User, due to picture->user->user_profile->mugshot.)
Remove Picture relationships.
Move beer models into core.

Removes UUIDField (closes #86).
Remove old column.
Remove last beerdb bits.
Move ThermoSummaryLog updates out of signal and into backend.