Remove util-extend dependecy.

lib/persistent-tunnel.js

@@ -1,12 +1,10 @@
 var net = require('net');
 var http = require('http');
-var extend = require('util-extend');
 var assert = require('assert');
 var NodeAgent = require('./_http_agent');
 
 function createTunnelConnection(options, cb) {
-  var proxyOptions = extend({}, options.proxy);
-
+  var proxyOptions = options.proxy || {};
   var connectOptions = {
     method: 'CONNECT',
     host: proxyOptions.host || 'localhost',

package.json

@@ -26,7 +26,5 @@
     "mocha": "^2.4.5",
     "node-tunnel": "^0.1.2"
   },
-  "dependencies": {
-    "util-extend": "^1.0.3"
-  }
+  "dependencies": {}
 }