Add OSC Plugin for openstack appcontainer pause

This change implements the "openstack appcontainer pause" command
 Based on existing zun command: zun pause

Partially Implements:blueprint zun-osc-plugin

Change-Id: I48a06b3a2e7945b9942cbaff51451d4068773d0f

setup.cfg

@@ -38,6 +38,7 @@ openstack.container.v1 =
    appcontainer_delete = zunclient.osc.v1.containers:DeleteContainer
    appcontainer_reboot = zunclient.osc.v1.containers:RebootContainer
    appcontainer_start = zunclient.osc.v1.containers:StartContainer
+   appcontainer_pause = zunclient.osc.v1.containers:PauseContainer
 
 [build_sphinx]
 source-dir = doc/source

zunclient/osc/v1/containers.py

@@ -249,3 +249,29 @@ class StartContainer(command.Command):
             except Exception as e:
                 print("Start for container %(container)s failed: %(e)s" %
                       {'container': container, 'e': e})
+
+
+class PauseContainer(command.Command):
+    """Pause specified container"""
+    log = logging.getLogger(__name__ + ".PauseContainer")
+
+    def get_parser(self, prog_name):
+        parser = super(PauseContainer, self).get_parser(prog_name)
+        parser.add_argument(
+            'container',
+            metavar='<container>',
+            nargs='+',
+            help='ID or name of the (container)s to pause.')
+        return parser
+
+    def take_action(self, parsed_args):
+        client = _get_client(self, parsed_args)
+        containers = parsed_args.container
+        for container in containers:
+            try:
+                client.containers.pause(container)
+                print(_('Request to pause container %s has been accepted')
+                      % container)
+            except Exception as e:
+                print("Pause for container %(container)s failed: %(e)s" %
+                      {'container': container, 'e': e})