Accounts: Get rid of PootleProfile.*_suggestion_count()
Accounts: Use AUTH_USER_MODEL in all User migration relations
initdb: Create directories before creating essential users

This fixes the issue of Directory.objects.root being called before
other models are loaded
Accounts: Use settings.AUTH_USER_MODEL in PootleProfile as well
Accounts: Get rid of is_staff everywhere
pootle_store/views: Simplify user/profile logic
docs: Get rid of a soon-to-be irrelevant warning in the api docs