* 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
This commit moves the user.Manage to its own package (user/manager)
so it can import the connector package in a later commit.
For clarity, it renames "Manager" to "UserManager" using gorname.
This commit has no functional changes.
