[Tracker] ISO extractor

[Christophe Fergeau <cfergeau redhat com>]

Hi,

libosinfo is a library which can inspect ISO images to find out if they
contain an OS installer, and can return the name of the OS. For Boxes, we'd
like to use tracker to get all the available ISOs on the system, and we'd
also like to get the OS information associated with the ISO from tracker.

To achieve this, I've written a simple extractor using libosinfo. I also
add some osinfo specific ontology, but since I'm totally unfamiliar with
that this will probably need to be reworked :)

Thanks for any comments about this code (coming in a separate email), and
please cc: me on answers as I'm not subscribed to the list

Christophe