RPM-based Distro support, parameter parser, numerous updates

Don,

as previously discussed, here is another pull request for puppet-cephdeploy. This comes with a number of additional changes compared to the first pull request; in order to make puppet-cephdeploy usable in the Puppet dashboard, I have added a parameter parser class. I did my best to maintain downward compatibility, so in fact, existing setups should just continue to work.

I have added a switch to make repository deployment configurable as per your request.

Plus, I have worked in the majority of Bastian Ballmann's changes, except for the one I fail to understand; once Bastian has clarified, I will add the according functionality as well. I have commented on individual commits if the purpose of them was not obvious (as in fixing typos or something), but should you have any additional questions, please don't hesitate to ask. Thank you very much again!