Modified time plugin, add to client and user
User Schema: findByUsername
Fixed too fast modified time test

Sometimes NodeJS/MongoDB would be too fast and update the document in the same
milisecond as the original save. Therefore, the modified time would be
identical and the test would fail sometimes.
Working OADA OAuth 2.0 server

Does normal OAuth 2.0 with OADA client discovery and JWT based client secrets.