Add domain, division and entity for Public Knowledge Workshop: General
Fix #452: rename local_home to entity_home
Replace profile.locality by a many-to-many field: entities

Added through a Membership class that includes an is_editor field instead of
profile.is_editor, because a user can be an editor in one entity and not an
editor in another.

This means there are currently two many-to-many relationships between profile
and entity: through Membership and through Candidate. This should be fixed in
the future (see #454).

Also added an entity parameter to profile.is_candidate and added a method
profile.is_editor which also has an entity parameter.

Work is not complete yet. Still need to replace occurrences of 'locality',
is_candidate and is_editor.
Removed is_editor from Admin interface for User, but it still needs to be added
as a field in the profile inline: this can be done by nested inlines (currently
not supported in our version of Django) or eliminating Profile altogether and
extending User instead (as done in Open Knesset).
Improving Membership table

Changin the connection to `user` instead of `profile` and adding some
more fields `can_answer` and `member_of`
More fixes for mutliple entities
Fix some tests
One error and 7 failures to go
Merge https://github.com/daonb/okqa into multi
Merge branch 'multi' of https://github.com/daonb/okqa into multi
imporve tests
Improve the user app and its tests
One more test passing
default entities
Fixed more tests

Several of them failed bacause we replaced lines setting the locality with lines
adding an entity, which resulted in multiple localities for one user, which is
an error which is discovered later when trying to get the locality.
Fix exceptions in tests
Fix another test failure
Fix even more tests
Fix another test
Pillow is a better Pil
removing a print stmt