/**
  * Responds to requests to POST /exercises/edit/{id}
  */
 public function postEdit(Request $request, $id)
 {
     $exercise = Exercise::find($id);
     $this->validateEditExercise($request, $exercise);
     Exercise::updateFromRequest($exercise, $request);
     \Session::flash('flash_message', 'Your changes were saved.');
     return redirect('exercises/edit/' . $id);
 }