[threeten-dev] ZoneId Z and TZ id UTC/GMT/UT

[Xueming Shen]

I believe the reasons that I failed to reproduce some of the reported test
failures locally before are

(1) Some systems have their default tz set to either UTC or GMT, so both
tests failed because the id of ZoneId for them are "Z", while the j.u.TZ has
"GMT" and/or "UTC" for them.

Stephen, I understand the reasoning behind picking "Z", but it's really an
"incompatible" choice, worth reconsidering?

(2) dtf prints the offset as "GMT +/-mm:nn" while JSR310 -> "+/-mm:nn"
      (GMT/UTC -> Z)

http://cr.openjdk.java.net/~sherman/jdk8_threeten/zondId_Z/

The change should fix the tests though.

-Sherman