Fix two bugs on SkinnyAPIController

 - haltWithBody for SkinnyApiController ignore status param
 - update/delete API responds as HTML when resource not found
Seamless Angular Server Side API support

 - Add several controller feature traits for Angular apps
 - Angular XSRF protection (XSRF-TOKEN cookie and X-XSRF-TOKEN header)
 - Angular friendly JSON keys (camelCase)
 - Merge JSON request body to params
 - Add Angular example code and test