Overlay bundles - download and install bundles from internet

For now this is just an idea.

The idea is to be possible to install bundles directly from internet. Of course, this means that the bundles should be provided as URLs which point to either 'tgz' or 'bundle.sh' or something like that.

The easiest and simplest method to implement this is by parsing the bundle name and if it starts with 'http', then download the file 'URL/bundle_online.sh'. This script should do everything else, e.g. download additional resources, build & pack, etc.

Of course, this introduces some security issues but this can be refined later.

Further refinement ideas are highly appreciated.