introduce Logging support

Author: stephenplusplus

docs/json/master/logging/.gitkeep

@@ -108,6 +108,34 @@ var apis = {
    */
   dns: require('./dns'),
 
+  /**
+   * <p class="notice">
+   *   **This is a *Beta* release of Google Cloud Logging for Google Compute
+   *   Engine.** This feature is not covered by any SLA or deprecation policy
+   *   and may be subject to backward-incompatible changes.
+   * </p>
+   *
+   * [Google Cloud Logging](https://cloud.google.com/logging/docs) collects and
+   * stores logs from applications and services on the Google Cloud Platform:
+   *
+   *   - Export your logs to Google Cloud Storage, Google BigQuery, or Google
+   *     Cloud Pub/Sub.
+   *   - Integrate third-party logs from your virtual machine instances by
+   *     installing the logging agent, `google-fluentd`.
+   *
+   * @type {module:logging}
+   *
+   * @return {module:logging}
+   *
+   * @example
+   * var gcloud = require('gcloud');
+   * var logging = gcloud.logging({
+   *   projectId: 'grape-spaceship-123',
+   *   keyFilename: '/path/to/keyfile.json'
+   * });
+   */
+  logging: require('./logging'),
+
   /**
    * [Google Cloud Pub/Sub](https://developers.google.com/pubsub/overview) is a
    * reliable, many-to-many, asynchronous messaging service from Google Cloud