Refactored model imports, etc.

This is in preparation for using database models only from `rattail` (i.e. no
`edbob`).  Mostly the model and enum imports were affected.

tailbone/grids/core.py

@@ -36,7 +36,7 @@ from webhelpers.html.builder import format_attrs
 
 from pyramid.renderers import render
 
-from edbob.core import Object
+from rattail.core import Object
 
 
 __all__ = ['Grid']

tailbone/grids/search.py

@@ -35,7 +35,7 @@ from pyramid.renderers import render
 from pyramid_simpleform import Form
 from pyramid_simpleform.renderers import FormRenderer
 
-from edbob.core import Object
+from rattail.core import Object
 from edbob.util import prettify