prompt.get promise: add test, update readme

.gitignore

@@ -1,3 +1,5 @@
 node_modules/
 node_modules/*
-npm-debug.log
+npm-debug.log
+
+package-lock.json

README.md

@@ -46,6 +46,12 @@ This will result in the following command-line output:
     email: [email protected]
 ```
 
+If no callback is passed to `prompt.get(schema)`, then it returns a `Promise`, so you can also write:
+```js
+const {username, email} = await prompt.get(['username', 'email']);
+```
+
+
 ### Prompting with Validation, Default Values, and More (Complex Properties)
 In addition to prompting the user with simple string prompts, there is a robust API for getting and validating complex information from a command-line prompt. Here's a quick sample:
 

test/prompt-test.js

@@ -12,6 +12,10 @@ var assert = require('assert'),
     macros = require('./macros'),
     schema = helpers.schema;
 
+// fix for vows, util.print/puts was removed from node
+require('util').print = console.log;
+require('util').puts = console.log;
+
 // A helper to pass fragments of our schema into prompt as full schemas.
 function grab () {
   var names = [].slice.call(arguments),
@@ -751,6 +755,22 @@ vows.describe('prompt').addBatch({
       }
     }
   }
+}).addBatch({
+  "when using prompt": {
+    "the get() method also works as a Promise": {
+      topic: function () {
+        var that = this;
+
+        prompt.override = { xyz: 468, abc: 123 };
+        prompt.get(['xyz', 'abc'])
+          .then(function (result) { return that.callback(null, result); });
+      },
+      "should respond with overrides": function (err, results) {
+        assert.isNull(err);
+        assert.deepEqual(results, { xyz: 468, abc: 123 });
+      }
+    }
+  }
 }).addBatch({
   "When using prompt": {
     "with fancy properties": {