With this change, an operator may be able to stop a
service container without stopping all services in a host.
This change is the starting point to start
fast-forward upgrades support.
In next changes new flags will be introducced to disable
stop dataplane services during upgrades.

Change-Id: Ifde7a39d7d8596ef0d7405ecf1ac1d49a459d9ef
Implements: blueprint support-stop-containers