Modernizr.load to asynchronous load Facebook, Twitter and Google+.

application.js

Modernizr.load([
  {
    load: '//platform.twitter.com/widgets.js'
  }, {
    load: '//apis.google.com/js/plusone.js'
  }, {
    load: '//connect.facebook.net/en_US/all.js',
    complete: function() {
      return FB.init({
        appId: '482807518397041',
        status: true,
        cookie: true,
        xfbml: true
      });
    }
  }
]);