GPII-217: added CORS middleware to support cross domain requests.
GPII-217: adding more comments for CORS middleware.
GPII-217: added tests for CORS middleware
Merge branch 'GPII-217' of github.com:yzen/kettle into GPII-217
Merge branch 'master' into GPII-217
Merge branch 'GPII-217'

* GPII-217:
  GPII-217: added tests for CORS middleware
  GPII-217: adding more comments for CORS middleware.
  GPII-217: added CORS middleware to support cross domain requests.