Add sitemap functionality and better documentation

spec/includes/pages_controller_include_spec.rb

@@ -0,0 +1,15 @@
+require 'spec_helper'
+
+class TestPagesController < ApplicationController
+  include Cmtool::Includes::PagesController
+end
+
+describe TestPagesController, type: :controller do
+  describe 'sitemap' do
+        it 'returns a proper sitemap' do
+          create_pages_tree
+          get :sitemap, format: 'xml'
+          expect( response.body ).to include "<url><loc>/en/child2.2</loc></url>"
+        end
+  end
+end