/**
  * Update the specified resource in storage.
  *
  * @param  Article  $article
  * @return Response
  */
 public function update(Article $article, CreateArticleRequest $request)
 {
     $article->update($request->all());
     $tagIds = $request->input('tag_list');
     $article->tags()->sync($tagIds);
     return redirect('articles');
 }