[api] add close event in ws-incoming.js

Author: jleal52

lib/http-proxy/passes/ws-incoming.js

@@ -96,6 +96,12 @@ var passes = exports;
 
     proxyReq.on('upgrade', function(proxyRes, proxySocket, proxyHead) {
       proxySocket.on('error', onOutgoingError);
+
+      // Allow us to listen when the websocket has completed
+      proxySocket.on('end', function () {
+        server.emit('close', proxyRes, proxySocket, proxyHead);
+      });
+
       // The pipe below will end proxySocket if socket closes cleanly, but not
       // if it errors (eg, vanishes from the net and starts returning
       // EHOSTUNREACH). We need to do that explicitly.