Header fixes. Hover tooltip on Mod/Admin (non-bootstrap). Mobile fixes

No scrollbar on main nav (unhides logout button).
Comment out unimplemented messages area.
Add icons to nav when in mobile (xs) (doesn't play nice on lg).
Use fa-file-excel-o to represent libs (an X instead of </>).
Merge pull request #334 from Zren/headerfixes

Header fixes. Hover tooltip on Mod/Admin w/ title attribute (Implements #259)