Make resources overridable

[sergiomichels]

A good option is to set an id to the resources of this plugin, like JQuery UI does, so the developer can override them. This is really useful for CSS changes, for example.

modules = {

        /* Bootstrap definitions without less (if resource processing is switched off) */
        'bootstrap' {
                resource id: 'bootstrap-jquery', url: [dir: 'bootstrap/js/tests/vendor',file: 'jquery.js']
                resource id: 'bootstrap-js',url: [dir: 'bootstrap/dist/js',                file: 'bootstrap.js']
                resource id: 'bootstrap-css',url: [dir: 'bootstrap/dist/css',                file: 'bootstrap.css']
        }

//application modules
modules = {
  overrides {
    'bootstrap' {
      resource id: 'bootstrap-css', url: [dir: 'css', file: 'my-custom-awesome-bootstrap.css']
    }
  }
}