[threeten-dev] Serialization of Chronology

[roger riggs]

Please review updates to address issues #283 and #279.

#283: Serialization of Chronology
#279 Inconsistent serialization for ISO chronology

Cleaned up serialization for all Chronologies and added tests.
Subclasses are enabled (as is ISOChronology) to use the Ser mechanism of 
Chronology.

Webrev:
    http://cr.openjdk.java.net/~rriggs/webrev-serialization-283/

Thanks, Roger