Refresh relevant pages when the user logs in with new information. NOTE: I'm not totally sure about the string I added

Per #61, there was some wonky stuff that was happening with respect to logging in and pages being cached.  In order to fix that I tagged comments and feeds with the user that they were acquired for.  If those differ from the current user then that content will be loaded.  This will probably result in slightly slower load times, but I think the gain in consistency is worth it.

Also, I added a string to tell the user he or she has successfully logged in.  I don't love the wording, but it was the best I could think of.  Suggestions are especially welcome there.