face: "Closing" WebSocket face when WebSocket tunnel closes

Change-Id: Ief2d643b09469eac7fc92aa5139e41bcb8d1e210
Refs: #1637
diff --git a/daemon/face/websocket-channel.cpp b/daemon/face/websocket-channel.cpp
index f409dc9..5cf98f6 100644
--- a/daemon/face/websocket-channel.cpp
+++ b/daemon/face/websocket-channel.cpp
@@ -89,6 +89,7 @@
   ChannelFaceMap::iterator it = m_channelFaces.find(hdl);
   if (it != m_channelFaces.end())
     {
+      it->second->close();
       NFD_LOG_DEBUG("handleClose: remove client");
       m_channelFaces.erase(it);
     }