[cfid-531] Fix ScimGroupEndpointsTests to run faster

Moved the database setup and tear down logic to static methods that will be called only
once for the entire suite of tests.
[cfid-658] Remove user_id, user_name and email from client tokens

Exclude user-specific attributes from refresh and access tokens for client_credentials
grant.
Fix broken test.
Merge branch 'develop' of github.com:cloudfoundry/uaa into develop