Remove greenkeeper badge from README

Author: blakeembrey

README.md

@@ -4,7 +4,6 @@
 [![NPM downloads][downloads-image]][downloads-url]
 [![Build status][travis-image]][travis-url]
 [![Test coverage][coveralls-image]][coveralls-url]
-[![Greenkeeper badge](https://badges.greenkeeper.io/blakeembrey/array-flatten.svg)](https://greenkeeper.io/)
 
 > Flatten nested arrays.