Fix Bug 1032013 - stop persisting watched repos

This change stops persisting watched repos.  You can add repos to a watch list on the toolbar, if you want.  But if you choose to just open several Firefox tabs for each repo, you don't get the long list of watched repos in each one.  This moves the workflow back closer to TBPL.

Let's not merge this yet until we have had Ed or Phil play with it and see if the workflow is right.