Implement first version of ExamMainController using a StackedController
Implement proper locking for the exam editor using the new AlreadyLockedException
Improve locking: provide exception free contructor for cases when no exception can be thrown
Proper naming for toolcontroller in exam view
Remove tools ans menu tree from exam editor
Remove button to launch editor from exam launch controller
Don't launch ExamLaunchController directly, but ExamMainController
Only show esf to normal users, not admins, authors or resource managers

Also update the beans context to use proper translation
Merge: Rework exam view by using controller stack; hide esf for non-students, fixes #13

* issue13:
  Only show esf to normal users, not admins, authors or resource managers
  Don't launch ExamLaunchController directly, but ExamMainController
  Remove button to launch editor from exam launch controller
  Remove tools ans menu tree from exam editor
  Proper naming for toolcontroller in exam view
  Improve locking: provide exception free contructor for cases when no exception can be thrown
  Implement proper locking for the exam editor using the new AlreadyLockedException
  Implement first version of ExamMainController using a StackedController
Correct spelling of english translation of exam type
Make StackedController breadcrumbs properly stylable by css