Load bundles from a bundle file

[llucax]

The app should be able to load bundles from a bundle text file specification.

At first, all media resources should probably be full remote URLs to avoid depending on reading local files or assets and be usable in both mobile and web.

Reading from the filesystem could be also an option to gets started more easily with mobile. URLs can also be interpreted as relative URLs to the bundle specification file.

Eventually bundle packages (for example, a ZIP file with the bundle specification + all the media files) could also be used for bundle distribution and in this case

Depends on a first implementation of: lunofono/lunofono_bundle#9

[llucax]

Depends on #29