Roundhouse Cleanup

This pull request cleans up some of the command line calls generated by the roundhouse helper.  String values get quoted now, and args that have not been specified are no longer passed to the command line.

Further down the road, I'd like to unify some of the command-line arg creation stuff in the various helpers by using UnionArgParser some more, because as it stands now the MSBuild and Roundhouse helpers have these huge methods that are mostly boilerplate.