Remove snyk badge and add dependencies badge

Snyk notoriously reports on the ms package used by socket.io, which
actually is no vulnerability, and the author rejected snyk's fix.
It looks bad on the README, so removing snyk until they fix their attitude.

Author: dashersw

README.md

@@ -1,10 +1,10 @@
 cote — A Node.js library for building zero-configuration microservices
 ====
 
-[![Known Vulnerabilities](https://snyk.io/test/npm/cote/badge.svg)](https://snyk.io/test/npm/cote)
 [![npm version](https://badge.fury.io/js/cote.svg)](https://badge.fury.io/js/cote)
 [![Build Status](https://travis-ci.org/dashersw/cote.svg?branch=master)](https://travis-ci.org/dashersw/cote)
 [![Coverage Status](https://coveralls.io/repos/github/dashersw/cote/badge.svg)](https://coveralls.io/github/dashersw/cote)
+[![dependencies Status](https://david-dm.org/dashersw/cote/status.svg)](https://david-dm.org/dashersw/cote)
 [![GitHub license](https://img.shields.io/badge/license-MIT-blue.svg)](https://raw.githubusercontent.com/dashersw/cote/master/LICENSE)
 
 **cote lets you write zero-configuration microservices in Node.js without nginx,