[ENH] Move the local storage expiry logic from the unread count into the base local storage component, apply expiry to favorites so it refreshes once in a while (multi-browser edge case), include the user in the key names so that it does not conflict between sessions

git-svn-id: file:///var/local/code.tiki.org/tikisvn/trunk@51345 b456876b-0849-0410-b77d-98878d47e9d5