/**
  * Update the specified grade in database.
  *
  * @param Request $request
  * @param Grade $grade
  * @return \Illuminate\Http\RedirectResponse
  */
 public function update(Request $request, Grade $grade)
 {
     $grade->update($request->all());
     return redirect()->action('AdminController@mark', ['submission' => $grade->submission_id]);
 }