Add failing testcase for single quotes in CMD

Closes #5701

This is due to @SvenDowideit comment at: https://github.com/docker/docker/issues/5701#issuecomment-58133541
where he asked for a testcase showing the error case.

Signed-off-by: Doug Davis <dug@us.ibm.com>
Merge pull request #8486 from duglin/Issue5701

Add failing testcase for single quotes in CMD