/**
  * Update the specified resource in storage.
  *
  * @param  Model    $model
  * @return Redirect
  */
 public function update(Model $model)
 {
     if ($this->form->update(Input::all())) {
         $redirectUrl = Input::get('exit') ? $model->indexUrl() : $model->editUrl();
         return Redirect::to($redirectUrl);
     }
     return Redirect::to($model->editUrl())->withInput()->withErrors($this->form->errors());
 }