Add version to PrintUsage output

[GoogleCodeExporter]

I would like to see an option or variable defined to allow for the code version 
to show up in the output, maybe something like:
getopt.Version = "2.5.1"

Original issue reported on code.google.com by jordan2...@gmail.com on 25 Nov 2014 at 5:45

[IzhakJakov]

+1