def update
      @article = Article.find(params[:id])
      if @article.update_attributes(params[:article])
        flash[:notice] = 'Article was successfully updated.'
      else
        @categories = Category.articles
      end
      respond_with(:admin, @article)
    end
def update
      @article = Article.find(params[:id])
      if @article.update_attributes(params[:article])
        flash[:notice] = 'Article was successfully updated.'
      else
        @categories = Category.articles
      end
      respond_with(:admin, @article)
    end
PUT /cornerstone/admin/articles/:id