Fix problem autoselect in team page
Cgroups are not experimental anymore.
Update admin manual about chroot

 - mono 'just works' in chroot
 - java isn't the only language in the world that needs a chroot
Updates to the API:

- /api/contest now also returns the freeze- and unfreezetime
- /api/submissions now does not return submissions during the freezetime when not requested by someone else than a jury member during freezetime (also fixed infreeze())
- Updated some API descriptions