Add a --signal option to the kill command to specify a signal.
Add a --signal option to the kill command to specify a signal.

Docker-DCO-1.1-Signed-off-by: Paul Lietar <paul@lietar.net> (github: plietar)
riyazdf/cli,Zebrilee/cli,thaJeztah/cli,allencloud/cli,docker/cli,thaJeztah/cli,dnephin/cli,cpuguy83/cli,allencloud/cli,riyazdf/cli,redpanda/cli,ashfall/cli,cpuguy83/cli,e11137/cli,redpanda/cli,ashfall/cli,e11137/cli,dnephin/cli,Zebrilee/cli,docker/cli