Bugfix in migration

It turns out that we can have suggestions without user. We can't merge
those, so just skip them.
Migration: Also get rid of stale contenttype for suggestion model
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
Profile: Display profile email for admin users
Profile: Get rid of unused fields
Migration: fixes postgress install

Store requires that pootle_app migration has already run and thus Directory is
available.  Other DBs seem to manage as they aren't as strict as Postgres. All
Postgres fans shout yay.