New newsroom administers don't see new newsroom

[smeranda]

If a user has submitted a news item in the past to a different newsroom and then is given administer/editor access to another newsroom, upon logging back in the user doesn't see the new newsroom navigation options.

Current workaround is for the user to navigate to /shortname/manage to "force" the administration navigation options.

[ericras]

Fix: when they are given admin access to a newsroom set users.newsroom_id in the database to the id of this newsroom