docs(readme): add Greenkeeper badge

https://greenkeeper.io/

README.md

@@ -2,6 +2,8 @@
 [![Coverage Status](https://coveralls.io/repos/telemark/tfk-utils-fix-address-for-seeiendom/badge.svg?branch=master&service=github)](https://coveralls.io/github/telemark/tfk-utils-fix-address-for-seeiendom?branch=master)
 [![js-standard-style](https://img.shields.io/badge/code%20style-standard-brightgreen.svg?style=flat)](https://github.com/feross/standard)
 # tfk-utils-fix-address-for-seeiendom
+
+[![Greenkeeper badge](https://badges.greenkeeper.io/telemark/tfk-utils-fix-address-for-seeiendom.svg)](https://greenkeeper.io/)
 Formats an address from [dsf](https://github.com/telemark/dsf) so [seeiendom](https://github.com/zrrrzzt/seeiendom) understands it.
 dsf will typically return ```Dream Street 48 D, 1732 Høtten``` and seeiendom needs ```Dream Street 48D, 1732 Høtten```
 This module removes the whitespace between house number and house letter.