engine: Update brick status to down when host down

When a host goes to non-operation state, update the
status of bricks on the host as down

Change-Id: Ib29f054c49962551773a63bf7484b4cee43de4de
Bug-Url: https://bugzilla.redhat.com/1021441
Signed-off-by: Sahina Bose <sabose@redhat.com>