Eager loading for AccessToken scopes

This seems to be necessary to avoid a with Jackson
serialization used by Spring OAuth2 which will result in:

failed to lazily initialize a collection of role: test.oauth2.AccessToken.scope, no session or session was closed. Stacktrace follows:
Message: Could not write JSON: failed to lazily initialize a collection of role: test.oauth2.AccessToken.scope, no session or session was closed; nested exception is org.codehaus.jackson.map.JsonMappingException: failed to lazily initialize a collection of role: test.oauth2.AccessToken.scope, no session or session was closed