Extend Skeleton functionality, including downloading from path

From discussions on https://github.com/puppetlabs/puppet/pull/2282 and the Forge triage with ashley.penney et al, there was discussion that it would be a nice feature to have a command within the module generator code that would generate a module from a given skeleton (such as https://github.com/garethr/puppet-module-skeleton).

This would mean little improvements wouldn't have to be merged into Puppet proper and there would be an easy way to go for best practise files to use within modules (.travis.yml file, Guardfile, .fixtures etc.)