Fix breaking bug on url joining resulting in paths like ///path.

Added OS-agnostic url join helper.

Author: STRML

lib/http-proxy/common.js

@@ -71,9 +71,7 @@ common.setupOutgoing = function(outgoing, options, req, forward) {
     ? url.parse(req.url).path
     : req.url;
 
-  outgoing.path = targetPath
-    ? targetPath + '/' + outgoingPath
-    : outgoingPath;
+  outgoing.path = common.urlJoin(targetPath, outgoingPath);
 
   return outgoing;
 };
@@ -109,4 +107,10 @@ common.getPort = function(req) {
   return res ?
     res[1] :
     req.connection.pair ? '443' : '80' ;
-}
+};
+
+// OS-agnostic join (doesn't break on URLs like path.join does on Windows)
+common.urlJoin = function() {
+  var args = Array.prototype.slice.call(arguments);
+  return args.join('/').replace(/\/+/g, '/');
+};