add option to run K with nailgun

@yilongli @osa1 please review

This pull request does not actually activate nailgun by default. In order to use nailgun, you must first set the K_NAILGUN environment variable. Once this is committed, I will experiment with the jenkins job to try to get it to run with nailgun.
What does this class do? There is no documentation and the name is not eloquent.