Added command line options for image file and command

Started the initial work to have command line options for the cli.  Image and command are required now and we can add options for debugging and other things terrible.
Stuff we can port are 
 - <image>,
 - <commands....>, 
 - env-file, env

Near future we can also port the "tty" options and "interactive" options so you can play around in an interactive docker container on top of taskcluster (again debugging).