title: window not defined with peer.js
body: <p>When I run my <code>node server.js</code> it gives me the following error:</p>
  
  <pre><code>/Users/Phil/Desktop/webrtc-core/node_modules/peerjs/lib/adapter.js:1
  le, __filename, __dirname) { module.exports.RTCSessionDescription = window.RTC
                                                                      ^
  ReferenceError: window is not defined
      at Object.&lt;anonymous&gt; (/Users/Phil/Desktop/webrtc-core/node_modules/peerjs/lib/adapter.js:1:102)
      at Module._compile (module.js:456:26)
      at Object.Module._extensions..js (module.js:474:10)
      at Module.load (module.js:356:32)
      at Function.Module._load (module.js:312:12)
      at Module.require (module.js:364:17)
      at require (module.js:380:17)
      at Object.&lt;anonymous&gt; (/Users/Phil/Desktop/webrtc-core/node_modules/peerjs/lib/util.js:5:25)
      at Module._compile (module.js:456:26)
      at Object.Module._extensions..js (module.js:474:10)
  </code></pre>
  
  <p>Isn't window defined in the adapter.js file?</p>