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>

pkg/api/validation/validation_test.go

@@ -1249,6 +1249,7 @@ func TestValidatePodSpec(t *testing.T) {
 				},
 			},
 			HostNetwork:   true,
+			HostIPC:       true,
 			RestartPolicy: api.RestartPolicyAlways,
 			DNSPolicy:     api.DNSClusterFirst,
 		},
@@ -1299,6 +1300,7 @@ func TestValidatePodSpec(t *testing.T) {
 				},
 			},
 			HostNetwork:   true,
+			HostIPC:       true,
 			RestartPolicy: api.RestartPolicyAlways,
 			DNSPolicy:     api.DNSClusterFirst,
 		},