* TestCreateClient was missing test coverage on error cases
* Fixed bug where 500s were being reported for bad requests
* changed function signature of NewAdminAPI back to old way of passing
in lots of repos: passing in a DbMap made it difficult to test
* added swappable ID and Secret generators when creating Clients
Admin API now requires a 128 byte base64 encoded secret to be passed in
Authorization header, closing up a potential security hole for those
who expose this service.