Adds the ability process a list of paths

* Returns an array of *all* paths from an array of paths
* Removes the dependency on stdlib
  * the 4.1.0 requirement made it uninstallable on PE

I don't see anything that makes the stdlib requirement necessary, but correct me if I missed something.

I am using a forked version of this in https://github.com/binford2k/puppetlabs-training-bootstrap/blob/9614ed8a89dc21acad3aacb457b9cee30e5deb2b/modules/advanced/lib/puppet/parser/functions/dirtree.rb but I'd like to just depend on your module.