add npm icons to readme

README.md

@@ -1,4 +1,6 @@
 [![Build Status](https://travis-ci.org/peers/peerjs-server.png?branch=master)](https://travis-ci.org/peers/peerjs-server)
+[![npm version](https://badge.fury.io/js/peer.svg)](https://www.npmjs.com/package/peer)
+[![Downloads](https://img.shields.io/npm/dm/peer.svg)](https://www.npmjs.com/package/peer)
 
 # PeerServer: A server for PeerJS #