docs(readme): add Greenkeeper badge

greenkeeper[bot] · greenkeeper[bot] · commit b064df2febea · 2017-05-11T19:06:01.000Z
diff --git a/README.md b/README.md
@@ -3,6 +3,8 @@
 
 # node-mount
 
+[![Greenkeeper badge](https://badges.greenkeeper.io/NodeOS/nodeos-mount.svg)](https://greenkeeper.io/)
+
 Mount/umount devices from node.js
 
 Really works on linux, may work on OS X, and will never work on windows.
