Add header for ci graphs and check that it is enabled

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/controllers/projects/application_controller.rb

 class Projects::ApplicationController < ApplicationController
   before_action :project
   before_action :repository
+  before_action :ci_enabled, only: :ci
   layout 'project'
 
   def authenticate_user!
@@ -25,4 +26,10 @@ class Projects::ApplicationController < ApplicationController
       )
     end
   end
+
+  private
+
+  def ci_enabled
+    return render_404 unless @project.gitlab_ci?
+  end
 end

app/views/projects/graphs/ci.html.haml

 - page_title "Continuous Integration", "Graphs"
+= render "header_title"
 = render 'head'
 #charts.ci-charts
   = render 'projects/graphs/ci/builds'