Remove unwanted import (which broke versioning)

ugh, now there's a check on startup to hopefully prevent this sort of
thing from sneaking up on us again

tailbone/auth.py

@@ -29,7 +29,6 @@ from __future__ import unicode_literals, absolute_import
 import logging
 
 from rattail import enum
-from rattail.db import model
 from rattail.util import prettify, NOTSET
 
 from zope.interface import implementer