Include websocket non-upgrade response

When the server do not accept the upgrade request for websockets the
response was previously not included and sent back. Now the proxy will
include the headers and the content from the server and the response in
these cases. Fixes http-party#890.

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

@@ -77,6 +77,24 @@ module.exports = {
    * @api private
    */
   stream : function stream(req, socket, options, head, server, clb) {
+
+    const createHttpHeader = function(line, headers) {
+      return Object.keys(headers).reduce(function (head, key) {
+        var value = headers[key];
+
+        if (!Array.isArray(value)) {
+          head.push(key + ': ' + value);
+          return head;
+        }
+
+        for (var i = 0; i < value.length; i++) {
+          head.push(key + ': ' + value[i]);
+        }
+        return head;
+      }, [line])
+      .join('\r\n') + '\r\n\r\n';
+    }
+
     common.setupSocket(socket);
 
     if (head && head.length) socket.unshift(head);
@@ -93,7 +111,10 @@ module.exports = {
     proxyReq.on('error', onOutgoingError);
     proxyReq.on('response', function (res) {
       // if upgrade event isn't going to happen, close the socket
-      if (!res.upgrade) socket.end();
+      if (!res.upgrade) {
+        socket.write(createHttpHeader('HTTP/' + res.httpVersion + ' ' + res.statusCode + ' ' + res.statusMessage, res.headers));
+        res.pipe(socket);
+      }
     });
 
     proxyReq.on('upgrade', function(proxyRes, proxySocket, proxyHead) {
@@ -119,22 +140,7 @@ module.exports = {
       // Remark: Handle writing the headers to the socket when switching protocols
       // Also handles when a header is an array
       //
-      socket.write(
-        Object.keys(proxyRes.headers).reduce(function (head, key) {
-          var value = proxyRes.headers[key];
-
-          if (!Array.isArray(value)) {
-            head.push(key + ': ' + value);
-            return head;
-          }
-
-          for (var i = 0; i < value.length; i++) {
-            head.push(key + ': ' + value[i]);
-          }
-          return head;
-        }, ['HTTP/1.1 101 Switching Protocols'])
-        .join('\r\n') + '\r\n\r\n'
-      );
+      socket.write(createHttpHeader('HTTP/1.1 101 Switching Protocols', proxyRes.headers));
 
       proxySocket.pipe(socket).pipe(proxySocket);