Added option to share kernel namespaces in libpod and podman

A pause container is added to the pod if the user opts in. The default pause image and command can be overridden. Pause containers are ignored in ps unless the -a option is present. Pod inspect and pod ps show shared namespaces and pause container. A pause container can't be removed with podman rm, and a pod can be removed if it only has a pause container.

Signed-off-by: haircommander <pehunt@redhat.com>

Closes: #1187
Approved by: mheon

completions/bash/podman

@@ -2077,6 +2077,9 @@ _podman_logout() {
 _podman_pod_create() {
   local options_with_args="
       --cgroup-parent
+      --share
+      --pause-command
+      --pause-image
       --podidfile
       --label-file
       --label
@@ -2085,6 +2088,7 @@ _podman_pod_create() {
   "
 
   local boolean_options="
+    --pause
   "
   _complete_ "$options_with_args" "$boolean_options"
 }