Vendor specific -release files are deprecated in favor of generic /etc/o...

...s-release files.

Fedora, openSUSE, RHEL, and SLES already ship /etc/os-release.

See http://www.freedesktop.org/software/systemd/man/os-release.html
for details about this file.

This patch adds inventory/linux.cf to parse the ID and VERSION_ID
fields of os-release and adds global classes for <ID> and
<ID>_<VERSION_ID>

It also adds inventory/suse.cf to distinguish between SUSE Linux
Enterprise and openSUSE.