Better readme and quickstart (#4)

added quickstart.js and a better README

container/snippets/quickstart.js

@@ -0,0 +1,42 @@
+// Copyright 2017, Google LLC 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.
+
+'use strict';
+
+const container = require('../src');
+
+if (
+  !process.env.GCLOUD_PROJECT ||
+  !process.env.GOOGLE_APPLICATION_CREDENTIALS
+) {
+  throw new Error(
+    'Usage: GCLOUD_PROJECT=<project_id> GOOGLE_APPLICATION_CREDENTIALS=<path to key json file> node #{$0}'
+  );
+}
+var projectId = process.env.GCLOUD_PROJECT;
+
+var client = new container.v1.ClusterManagerClient({
+  // optional auth parameters.
+});
+
+var projectId2 = projectId;
+var zone = 'us-central1-a';
+var request = {
+  projectId: projectId2,
+  zone: zone,
+};
+client.listClusters(request).then(responses => {
+  var response = responses[0];
+  console.log(response);
+});