Move redhat-management (spacewalk/satelite) support from core to contrib.

These vendor specific bits don't any longer belong in the core of Cobbler.
Moving stuff like this in modules/contrib/packages improves maintainability
of Cobbler, also we don't want to be biased towards any Linux vendor.
Merge pull request #1227 from jmaas/master

Move redhat-mgt (spacewalk/satelite) support from core to contrib.