Add logic to filter users that can record meetings, refs #804

Adding the method 'can_record_meeting?' to User. Now the 'join options' when
opening a webconf room are only shown if the user can record the meeting,
otherwise he's redirected to the standard join action.
Add missing view rooms/recordings, refs #804

It existed in BigbluebuttonRails but had not been added to Mconf-Web yet.
Add it and added links to show it and to fetch recordings for an specific
room.
Add a list of recordings for spaces, refs #804

Added as a subtab of the tab 'webconference'. Shows a list very similar to
the one shown for user rooms (added by f9987e43116).

Also introduced the class '.page-tabs' that can be used for menus that shows
page.
Add observer to create room metadata, refs #804

To make sure a web conference room will always have the basic metadata it
needs to work properly.

Also moved the observer methods for profiles to their own file.