Multivendor/distribution/OS support

In order to make this module usable on different platforms with different OS and distributions support for them should be added.

Support is planned for:

• Debian / Ubuntu
• RHEL Linux 5/6

more support can be added at a later point.

I'll move the package declaration and the detection of the ${::osfamily} to the params.ppfile. This file will be inherited later.

The detection is needed for different package names for RHEL and Debian.

I've started this work on a branch in my own repo.

• Multivendor branch

MacOS X/Darwin support will be provided at a later point of time as we need to do some refactoring in the module first (user/group related).

[robkinyon]

Pull request #17 adds centos and suse to the debian support that was already there. I did this by cloning alup/puppet-rbenv's solution.