Improve site map code implementation.

• Introduce a SiteMapNodeTypes class (same pattern as for NodeTypes)
• Change the nodeType definition :
  • Introduce mixIn for site map properties (Added to a page). Site map pages element should have a dedicated mixIn instead of 'dummy'
    property
  • Add properties to the sitemap nodeType
• Use a standard multivalue property to store the pages linked to a sitemap instead of a sub node with multiple properties.
• Increase site map coverage.
• Use pure Vaadin Item instead of JcrItems in the detail dialogs
  • Use the siteMap bean in the detail dialog
• Improve delete action
  • Unregister site map
  • Remove pages mixIn
• Configure default values (change frequency and priority)
  • default values have to be configured on siteMap level.

http://wiki.magnolia-cms.com/display/DEV/Concept+Google+SiteMap+M5