skip, show_stopper, all tested

* skip, If you want to skip any testcase you can just give "True"
  for this.

* show_stopper, testcase failed meaning we should not continue.
  If you are expecting too many failures because of this failure,
  you mark it as show_stopper: True

* all is special layer, that means all layers.

* -d/--delegate is an option to delegate validation to docker
  containers. docker containers will never use this.

Change-Id: I92b1fc0ac47a6ca3b75e1e2e75c9aea0d206fdaf
Signed-off-by: Naga Sugguna <ns156u@att.com>