Sort by group size (Mentioned in #306). Popular groups sortBy -size

Will lazily update over 2h after pushing.
Linkifies Popular Group heading. Depends on #332 for CSS.
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)
Add Script.installsSinceUpdate & show in author panel.
Merge pull request #333 from Zren/installssinceupdate

Add Script.installsSinceUpdate & show in author panel.
Merge pull request #335 from Zren/groupsize

Sort by group size (Mentioned in #306). Popular groups sortBy -size