Currently, when stoping/restarting container, Kolla uses default timeout value
between SIGTERM and SIGKILL provided by docker which is 10 sec. But some
services require more than it to finish graceful shutdown progress.

This patchset adds graceful_timeout to kolla_docker to override the default
one.

Partial Implements: bp signaling-to-container

Change-Id: Ica0b48a53c650cc23dfa1955027d2cf936a5932f