Add dateformat flow stub

Summary: `flow-typed create-stub dateformat`

Reviewed By: passy

Differential Revision: D16334489

fbshipit-source-id: d72b89a6578913bb799f93038455e16e386a7422

src/utils/CertificateProvider.js

@@ -21,7 +21,6 @@ import iosUtil from '../fb-stubs/iOSContainerUtility';
 import {reportPlatformFailures} from './metrics';
 import {getAdbClient} from './adbClient';
 import * as androidUtil from './androidContainerUtility';
-// $FlowFixMe T47375728
 import dateFormat from 'dateformat';
 const writeFile = promisify(fs.writeFile);
 const exists = promisify(fs.exists);