principal: action class and registry addition

* Adds new registry for access actions.

Signed-off-by: Jiri Kuncar <jiri.kuncar@cern.ch>
base: dropdown menu and mobile UI

* Makes admin menu looks embadded in dropdown. (closes #1994)
* Fixes messages dropdown

Signed-off-by: Adrian Pawel Baran <adrian.pawel.baran@cern.ch>