Use pify

I didn't realize the `util.promisify` polyfill was so bloated...

Author: sindresorhus

index.js

@@ -2,9 +2,9 @@
 const fs = require('fs');
 const path = require('path');
 const parseJson = require('parse-json');
-const promisify = require('util.promisify');
+const pify = require('pify');
 
-const readFileAsync = promisify(fs.readFile);
+const readFileAsync = pify(fs.readFile);
 
 module.exports = options => {
 	options = Object.assign({

package.json

@@ -33,7 +33,7 @@
 	"dependencies": {
 		"normalize-package-data": "^2.3.2",
 		"parse-json": "^4.0.0",
-		"util.promisify": "^1.0.0"
+		"pify": "^3.0.0"
 	},
 	"devDependencies": {
 		"ava": "*",