Base#prompt now return a promise

Author: SBoudrias

lib/base.js

@@ -223,24 +223,20 @@ Base.prototype.welcome = deprecate(
  * user's answers as defaults.
  *
  * @param  {array} questions  Array of question descriptor objects. See {@link https://github.com/SBoudrias/Inquirer.js/blob/master/README.md Documentation}
- * @param  {Function} callback  Receive a question object
- * @return {this}
+ * @return {Promise}
  */
 
-Base.prototype.prompt = function (questions, callback) {
+Base.prototype.prompt = function (questions) {
   questions = promptSuggestion.prefillQuestions(this._globalConfig, questions);
 
-  this.env.adapter.prompt(questions, function (answers) {
+  return this.env.adapter.prompt(questions).then(function (answers) {
     if (!this.options['skip-cache']) {
       promptSuggestion.storeAnswers(this._globalConfig, questions, answers);
     }
 
-    if (_.isFunction(callback)) {
-      callback(answers);
-    }
+    return answers;
   }.bind(this));
 
-  return this;
 };
 
 /**