docker_cli/restart: Fix two test bugs

* Test had code to check speed of container state transition
  and fail test if it was too quick or too slow.  However,
  the durations were mistakenly being compared to a string
  and not an number.

* The stop sub-subtest was failing due to an un-reported
  bug, opened bugzilla 1165866.

Signed-off-by: Chris Evich <cevich@redhat.com>
Merge pull request #421 from cevich/restart_fix

docker_cli/restart: Fix two test bugs