Region bugfixes: 1115321, 1115244, 1115238, 1115274, 1115309

Bug 1115321 - Fix zone name in gear_groups rest api response
Bug 1115244 - Add 'region' as optional param to ADD_APPLICATION link
Bug 1115238 - Add DEFAULT_REGION_NAME param to the broker configuration.
Bug 1115274 - Fix 'default' field in /regions REST api
Bug 1115309 - Default region will be selected when optional param 'region' is not set during app creation.