Add TRIPLEO_KOLLA_UMASK for custom umask settings

Allow execution of the kolla_start script with
a given umask settings. Virtqemud container requires this
at the least, as libvirt/qemu dynamic permissions should
be restricted to not create VM files world readable.

Change-Id: Iaa09a8a4cad12d49007ea92ea0922597916981af
Signed-off-by: Bogdan Dobrelya <bdobreli@redhat.com>
(cherry picked from commit 8aa57665b5)

container-images/kolla/base/start.sh

@@ -15,4 +15,5 @@ if [[ ! "${!KOLLA_SKIP_EXTEND_START[@]}" ]]; then
 fi
 
 echo "Running command: '${CMD}${ARGS:+ $ARGS}'"
+umask "${TRIPLEO_KOLLA_UMASK:-0022}"
 exec ${CMD} ${ARGS}