[threeten-dev] Review fix for periodUntil issue 273

[roger riggs]

Please review bug fix/improvements for:

PeriodUntil throws exception: unable to calculate period between objects 
of different types
     http://cr.openjdk.java.net/~rriggs/webrev-fix-perioduntil-273/


The periodUntil methods do not correctly compute the period
for HijrahDate, ThaiBuddistDate, MinguoDate, and JapaneseDate.
ChronoDateImpl is enhanced to support 12 month based calendars.

The ValueRange.getIntValue method should throw similar exceptions
when the field is not an int field. Provides better feedback for
the generic Temporal.get access to fields that are not int field.

Added simple tests to TestHijrahChronology, TestJapaneseChronology,
TestMinguoChronology, and TestHijrahChronology

Thanks, Roger