Add reverse proxy endpoint.

It works by using the Host of the request. When it receives something in
the form of: `<node>.<session>.play-with-docker.com` it does a reverse
proxy http request to `node`, validating that the `node` actually belongs
to the `session`.
If the node has a prefix `ip` and continues with a valid IP address
where the dots where replaces by underscores (like `ip10_0_0_1`) then it
will remove the `ip` prefix and and replace the underscores by dots, and
assume it is an ip address.

services/docker.go

@@ -52,6 +52,17 @@ func CreateNetwork(name string) error {
 
 	return nil
 }
+func ConnectNetwork(containerId, networkId string) error {
+	err := c.NetworkConnect(context.Background(), networkId, containerId, &network.EndpointSettings{})
+
+	if err != nil {
+		log.Printf("Connection container to network err [%s]\n", err)
+
+		return err
+	}
+
+	return nil
+}
 
 func DeleteNetwork(id string) error {
 	err := c.NetworkRemove(context.Background(), id)