RFR: 8072379: Implement jdk.Version and jdk.OracleVersion

[Iris Clark]

Hi, Joe.

> I suggest changing the class-level javadoc discussing comparisons 
> to defer to the various compare methods. It would be helpful to 
> not which compare methods are consistent with equals and which 
> are not.

I've reworked the class and method javadoc for the comparison 
methods so that comparison details exist in only one place.  I
believe that this resolves the remaining spec issue to get an
initial implementation of jdk.Version into jdk9/dev.

After I've enhanced the regular expression as suggested
elsewhere in this thread I'll post the updated webrev.  
 
Thanks,
iris