Re-implement openurlwithproxy.js example

This patch adds example which illustrates running chromium with
proxy server.

examples/openurlwithproxy.js

@@ -0,0 +1,42 @@
+/**
+ * Copyright 2017 Google Inc., PhantomJS Authors All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+var Browser = require('../lib/Browser');
+
+if (process.argv.length < 5) {
+    console.log('Usage: openurlwithproxy.js <proxyHost> <proxyPort> <URL>');
+    return;
+}
+
+var host = process.argv[2];
+var port = process.argv[3];
+var address = process.argv[4];
+
+var browser = new Browser({
+    args: [
+        `--proxy-server=${host}:${port}`;
+    ]
+});
+browser.newPage().then(async page => {
+    var success = await page.navigate(address);
+    if (success) {
+        console.log('Page title is ' + (await page.title()));
+    } else {
+        console.log('FAIL to load the address "' +
+            address + '" using proxy "' + host + ':' + port + '"');
+    }
+    browser.close();
+});