When absolute paths are specified, it could be useful to have the chance to specify different paths for different hostnames.
Example: suppose that a package has an absolute path for a given executable. However, we know that this executable is in different places on different machines. depending on the hostname, the manifest could return different paths.
Workaround for executable groups: have it run a packaged script that launches the proper executable depending on the hostname. This does not work for resources.
