Fix config.json and add favicon support

/to @bajtos or @ritch 

The PR fixes 3 issues:
- Make sure the app is listening on 0.0.0.0:3000 instead of localhost:3000
- Add favicon middleware to avoid 404 warnings
- Fixes https://github.com/strongloop/generator-loopback/issues/12
3000 is the default port used by loopback-boot, this entry is redundant.

It is a bad idea to use `0.0.0.0` because of Windows: LoopBack app will print the URL `http://0.0.0.0/`, but the browsers on Windows cannot resolve such address. You should use `undefined` host, in which case the LoopBack app will use `localhost` for the URL.

Alternatively, add another entry `{ name: 'url', value: 'http://localhost:3000/' }`.