Support pods with containers using host ipc

Add a HostIPC field to the Pod Spec to create containers sharing
the same ipc of the host.

This feature must be explicitly enabled in apiserver using the
option host-ipc-sources.

Signed-off-by: Federico Simoncelli <fsimonce@redhat.com>

hack/verify-flags/known-flags.txt

@@ -107,6 +107,7 @@ deployment-controller-sync-period
 hostname-override
 host-network-sources
 host-pid-sources
+host-ipc-sources
 http-check-frequency
 http-port
 ignore-not-found