`docker kill 123` will show something like:
`Error response from daemon: Cannot kill container 123: nosuchcontainer: No such container: 123`
Notice the `nosuchcontainer` text, that should not be there as that's an internal ID that means nothing to the end user.
This PR fixes this by using `util.GetErrorMessage()` to extract just the message.
While in that dir I found a couple of other spots that could use the same call, just to be safe.
Signed-off-by: Doug Davis <dug@us.ibm.com>
Doug Davis