make upnp take asio context

Change-Id: Ie039a084d04dee1a1bfcda5865b6482f272ccfe3
diff --git a/include/upnp/upnp_control.h b/include/upnp/upnp_control.h
index 10e44e3..e68cada 100644
--- a/include/upnp/upnp_control.h
+++ b/include/upnp/upnp_control.h
@@ -40,7 +40,7 @@
 class Controller
 {
 public:
-    Controller();
+    Controller(const std::shared_ptr<UPnPContext>& ctx);
     ~Controller();
 
     // Set known public address