Fabric: Add new commands send_file and migrate_app

Also added some prints to other commands so we get feedback when running
them.
Unit: Use 'url' to identify the user url, rather than 'profile_url'
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