Feature/user relationships

Messages used to just be messages until @housewifehacker contributed code that added User and Package relationships to them.  All messages in our production DB since that code was introduced have those relationships in place.

However, messages from before that time don't have those relationships; queries for messages belonging to a user before February 2013 don't show up (even though the messages are there).

This upgrade script simply steps through all those old messages and adds User/Package relationships where they should be (completing the historic data).