Improve $OPT on current EA builds

[Michael Osipov]

Hi folks,

just tried Java 9 build 99 and noticed that $OPT of JEP 223 is not 
easily parseable/not a valid ISO date:

java --version
> Java(TM) SE Runtime Environment (build 9-ea+99-2015-12-23-183325.javare.4146.nc)

Can you kindly file an issue to make that a proper basic ISO datetime 
string? Date format would be here yyyyMMdd'T'HHmmss'Z' with timezone 
Etc/UTC as in DateTimeFormatter#basicDateTimeNoMillis.

Michael