chore(Gruntfile): run webserver on 0.0.0.0

... so that we can access it from local VMs.

The security risk of doing this is very low since only the current
working directory is being made accessible to everyone. There is also
an option to run a local firewall, which is a better way to secure the
developer's machine anyway.

Gruntfile.js

@@ -25,7 +25,7 @@ module.exports = function(grunt) {
       devserver: {
         options: {
           port: 8000,
-          hostname: 'localhost',
+          hostname: '0.0.0.0',
           base: '.',
           keepalive: true,
           middleware: function(connect, options){