Update container resolv.conf when host network changes /etc/resolv.conf

Only modifies non-running containers resolv.conf bind mount, and only if
the container has an unmodified resolv.conf compared to its contents at
container start time (so we don't overwrite manual/automated changes
within the container runtime). For containers which are running when
the host resolv.conf changes, the update will only be applied to the
container version of resolv.conf when the container is "bounced" down
and back up (e.g. stop/start or restart)

Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)