GROOVY-6675 : Base script support for JCommander annotation-based parameters

As the jira explains [http://jira.codehaus.org/browse/GROOVY-6675], we need a base script in Groovy to support super cool declarative scripts that use annotations to define the argument parsing into parameters.   The base script is `groovy.cli.JCommanderScript` which provides JCommander annotations which we use because Apache CLI doesn't have any yet.  JCommander is already in Groovy because of TestNG so we put this class there so that it doesn't change anything for folks that don't have/want JCommander.

This PR also bumps TestNG to 6.8.8 and JCommander to 1.35.