build: Always build in C++11 mode.

This commit also includes update of websocketpp submodule, as the
previous version has compilation problems on OSX with XCode 6.1

Change-Id: I8c9670d0026d840838d77e610e50679ee5ede7a5
Refs: #1930, #2082
diff --git a/daemon/face/websocket-channel.cpp b/daemon/face/websocket-channel.cpp
index d6cf64b..a16ee64 100644
--- a/daemon/face/websocket-channel.cpp
+++ b/daemon/face/websocket-channel.cpp
@@ -115,8 +115,8 @@
       websocketpp::lib::error_code ecode;
       m_server.close(hdl, websocketpp::close::status::normal, "closed by channel", ecode);
     }
-  shared_ptr<WebSocketFace> face = make_shared<WebSocketFace>(FaceUri(remote), this->getUri(),
-                                                              hdl, ref(m_server));
+  shared_ptr<WebSocketFace> face = ndn::make_shared<WebSocketFace>(FaceUri(remote), this->getUri(),
+                                                                   hdl, ref(m_server));
   m_onFaceCreatedCallback(face);
   m_channelFaces[hdl] = face;