title: can't get Next.js to work with custom hostname
body: <p>when I run <code>npm run dev -- -H 192.168.1.100</code> I got this error</p>
  
  <pre><code>{ Error: listen EADDRNOTAVAIL: address not available 192.168.1.100:3000
      at Server.setupListenHandle [as _listen2] (net.js:1273:19)
      at listenInCluster (net.js:1338:12)
      at doListen (net.js:1471:7)
      at process._tickCallback (internal/process/next_tick.js:63:19)
    code: 'EADDRNOTAVAIL',
    errno: 'EADDRNOTAVAIL',
    syscall: 'listen',
    address: '192.168.1.100',
    port: 3000 }
  </code></pre>
  
  <p>this the <code>package.json</code></p>
  
  <pre><code>{
    "name": "Edel",
    "version": "1.0.0",
    "description": "",
    "main": "index.js",
    "scripts": {
      "dev": "next",
      "build": "next build",
      "start": "next start"
    },
    "keywords": [],
    "author": "",
    "license": "ISC",
    "dependencies": {
      "next": "^7.0.2",
      "react": "^16.7.0",
      "react-dom": "^16.7.0"
    }
  }
  </code></pre>