fixup better exception
Clean up get_instance_user

Make get_instance_user more readable

By using a get() query, this will run a maximum of one query, whereas previously, for the common case where a single InstanceUser exists, two queries will run.
Add a save() convenience method to InstanceUser

For the same reasons that it exists on User
Move InstanceDataCommand out of underscore module
Comment and minor adjustment

prefern stdout.write over print
Convert nonexistent god_role -> commander_role
Handle duplicate email imports from otm1

Fix how more_permissions reinstates previous roles
Drop out save with system user
Great big separate app commit
Fix lint