Add an option to control if play kube should start the pod

Having play kube start the pod is not always appropriate, one might
for example like to have the pod running as a set of systemd services.
Add a `start` option to the command line and API to control if the pod
should be started or not; it defaults to true for backward
compatibility.

Signed-off-by: Alban Bedel <albeu@free.fr>

pkg/api/server/register_play.go

@@ -29,6 +29,11 @@ func (s *APIServer) registerPlayHandlers(r *mux.Router) error {
 	//    name: logDriver
 	//    type: string
 	//    description: Logging driver for the containers in the pod.
+	//  - in: query
+	//    name: start
+	//    type: boolean
+	//    default: true
+	//    description: Start the pod after creating it.
 	//  - in: body
 	//    name: request
 	//    description: Kubernetes YAML file.