puppetlabs-ruby module should be able to set default version

The puppetlabs-ruby module can use ruby-switch to change the system default version of ruby in some circumstances, but this package is not available for all operation systems, distributions, or even release versions. (it's horrible and I wrote it)

The ruby module should have a method that changes the system default ruby for all supported operating systems.

e.g. Use update-alternate with Ubuntu.