[threeten-dev] Review for #221 Clock has too many abstract methods

[Roger Riggs]

Please review fix for #221 Clock as too many abstract methods

Webrev:
   http://cr.openjdk.java.net/~rriggs/webrev-clock-221/

Javadoc:
   http://cr.openjdk.java.net/~rriggs/javadoc-clock-221/

Thanks, Roger