Support for installing spacewalk-proxy

[optiz0r]

This module does a good job of installing the main service, it would be useful to be able to install proxies too. I've thrown together a first attempt at this here https://github.com/optiz0r/puppet-spacewalk/tree/proxy_support (although it's lacking in docs, tests etc)

[CommanderK5]

Hi,
Looks good, feel free to submit a PR whenever you're ready. We can work on tests and docs later on.