Update README.md

Removed david-dm badges because david-dm is down: alanshaw/david#179

Author: Semigradsky

README.md

@@ -6,9 +6,6 @@
 [![coverage status](https://coveralls.io/repos/zaggino/z-schema/badge.svg)](https://coveralls.io/r/zaggino/z-schema)
 
 [![Greenkeeper badge](https://badges.greenkeeper.io/zaggino/z-schema.svg)](https://greenkeeper.io/)
-[![dependencies Status](https://david-dm.org/zaggino/z-schema/status.svg)](https://david-dm.org/zaggino/z-schema)
-[![devDependencies Status](https://david-dm.org/zaggino/z-schema/dev-status.svg)](https://david-dm.org/zaggino/z-schema?type=dev)
-[![optionalDependencies Status](https://david-dm.org/zaggino/z-schema/optional-status.svg)](https://david-dm.org/zaggino/z-schema?type=optional)
 
 [![NPM](https://nodei.co/npm/z-schema.png?downloads=true&downloadRank=true)](https://nodei.co/npm/z-schema/)