[threeten-dev] Review for changes to JulianFields and QuarterOfYear unit

[Roger Riggs]

Addressing changes in:

#177  Refactor JulianDayFeild enum to Julian Fields
     Renamed and refactored
#183 Rename WeekDefinition to WeekFields
     Renamed and refactored
#180 Reduce set of ChronoUnits
     Removed HALF_YEARS
     Moved QUARTER_YEARS to ISOFields

http://cr.openjdk.java.net/~rriggs/webrev-units/

Comments, please.

Roger