removed home controller in the admin namespace.
Function can be taken over by the base_controller in the admin namespace.
fixed forgotten reference to replaced home controller
Added cucumber feature for the admin control panel
Testing for proper behaviour when trying to access the admin control panel
  - as visitor (not logged in) => redirect to login page
  - as user without admin role => raise "Access Denied Error" and redirect
    to homepage
  - as admin user => show admin control panel homepage
removed test for getting index page from base controller since this is already tested in cucumber
Merge branch 'feature/admin-panel' into develop

Basic admin panel including testing framework in place.
Admin panel can only be accessed by admin user and redirects to appropriate sites for non-admins or
non-users.