[Rpm-metadata] removeable media tagging

[seth vidal]

Hi folks,
 Something jeremy mentioned today got me thinking about how to add
removable media information to the repomd metadata.

A couple of solutions occurred to me:
1. have a program that runs through the media breakout and already-
generated metadata and add in a media entry to the primary.xml then
regenerates the repomd.xml
2. have a separate file in the metadata directory for removeable media
that just has pkgid: media/device

in number one we're loading up the metadata itself as part of
(potentially) the location tag as to where to find it. This has the
advantage of being straightforward to understand and only causes some
minor semantic changes to the metadata. 

in number two we're making a separate file that stores this information.
It'll be quicker to index that to sort out how to either ask for the
media or another way to order them. And it's just a simple format to
figure out.

Thoughts either way?

-sv