Stash: ensure user does not run out of messages

* Reload if we run out of messages
* Provide more messages than the limit so that reloading is needed only
  rarely
* Remove untranslated class from translated messages

Change-Id: I768082c54600653d7b5cb4f58b4c55822a2acc01
Merge "Stash: ensure user does not run out of messages"