Add Oracle Network and SuSE Manager support to documentation

[dagwieers]

mrepo (rhnget) supports Red Hat Network (RHN) and since both Oracle and Novell based their offering on Red Hat's RHN product, as a result mrepo works equally well with Oracle's Unbreakable Linux Network (ULN) and Novell's SuSE Manager (NU).

The configuration for the various backends are:

• Red Hat Network: xmlrpc.rhn.redhat.com
• Oracle Unbreakable Linux Network: linux-update.oracle.com
• Novell SuSE Manager: nu.novell.com

For Spacewalk you simply use your local spacewalk server.

[fmcardosom]

Mrepo can be used in conjunction with Spacewalk also for Oracle Public Repositories;

http://public-yum.oracle.com/

[Djelibeybi]

I've added support for ULN including documentation and sample dist config files and issued a pull request: #61