Add missing JSON schema for 'refs' and 'branch_name'

Fixes #325

test/test_api_usage.py

@@ -2989,6 +2989,13 @@ class TestBuildTriggers(ApiTestCase):
     build_obj = database.RepositoryBuild.get(database.RepositoryBuild.uuid == start_json['id'])
     self.assertEquals('bar', py_json.loads(build_obj.job_config)['trigger_metadata']['foo'])
 
+    # Start another manual build, with a ref.
+    start_json = self.postJsonResponse(ActivateBuildTrigger,
+                                       params=dict(repository=ADMIN_ACCESS_USER + '/simple',
+                                                   trigger_uuid=trigger.uuid),
+                                       data=dict(refs=[{'kind': 'branch', 'name': 'foobar'}]),
+                                       expected_code=201)
+
   def test_invalid_robot_account(self):
     self.login(ADMIN_ACCESS_USER)