title: Nodebb web app has failed to start and just crashes
body: <p>I managed to install the nodebb forum very well and i was able to use it... On the next day , it failed to start and just crashes. I think my problem was that connect mongo cannot easily connect to mongodb database. probably help me look at this error.</p>
  
  <pre>
      16/2 20:26 [4171] - info: Launching web installer on port 4567
  
  events.js:72
          throw er; // Unhandled 'error' event
   Error: listen EADDRINUSE
      at errnoException (net.js:905:11)
      at Server._listen2 (net.js:1043:14)
      at listen (net.js:1065:10)
      at Server.listen (net.js:1139:5)
      at EventEmitter.listen (/home/goldsoft25/Desktop/NodeJS/NodeBB-master/node_modules/express/lib/application.js:617:24)
      at launchExpress (/home/goldsoft25/Desktop/NodeJS/NodeBB-master/install/web.js:53:15)
  </pre>