Merge pull request #1 from maracuja-juice/patch-1

add list issue labels method

lib/Issue.js

@@ -212,6 +212,18 @@ class Issue extends Requestable {
    listLabels(options, cb) {
       return this._request('GET', `/repos/${this.__repository}/labels`, options, cb);
    }
+
+   /**
+   * List the labels of a particular issue
+   * @see https://developer.github.com/v3/issues/labels/#list-labels-on-an-issue
+   * @param {number} issue - the id of the issue to get comments from
+   * @param {Object} data ...
+   * @param {Requestable.callback} [cb] - will receive the comments
+   * @return {Promise} - the promise for the http request
+   */
+   listIssueLabels(issue, data, cb) {
+      return this._request('GET', `/repos/${this.__repository}/issues/${issue}/labels`, data, cb);
+   }
 
   /**
    * Get a label