Porting plugin methods from 0.3.x to 1.0

* `locator.getBundleResources()`: to filter resources per bundle. e.g.: this is used
  by consumers to collect all templates from a given bundle.
* `locator.getBundleFiles()`: to filter files per bundle. e.g.: this is used by consumers
  to collect all css files from a given bundle.
Hmm... the old API for files in a bundle didn't have type either, so nevermind.