bug 855423 Change all RAISE ERROR -> NOTICE in stored procs

* Add alembic migration (yay!)
* Fix a test that no longer needs to expect an exception

TO TEST MIGRATION: 

upgrading: 
PYTHONPATH=. alembic --config=config/alembic.ini upgrade head

downgrading: 
PYTHONPATH=. alembic --config=config/alembic.ini downgrade -1

upgrade & downgrade run functions and also change a value in a table called 'alembic_version'.