Revert --stop/--kill and use --timeout instead

Reverts #6987 and instead uses a --timeout option to specify the wait
time.
Default timeout is set to 5 seconds

Docker-DCO-1.1-Signed-off-by: Brian Goff <cpuguy83@gmail.com> (github: cpuguy83)
Remove the "a". But the phrasing is a little off because subject and object are mixed up. It makes it sound like the timeout parameter is waiting for a container to do something. Maybe try something like: "When using `force`, you can now specify a period of time to wait before removing a running container by using the `timeout` parameter.

Also, what values does the parameter take? Just seconds? hh:mm:ss? Something else?