Ubuntu Precise support, hiera dependency removal, readme enhancements

Hi Dennis.

Thanks for your work on this module. I've made the following changes on it:

* Ubuntu Precise support

I added a new template to deal with Ubuntu Precise. I also added it in the supported OS codenames.

* Hiera

I haven't heard of hiera until I saw your code. I researched a bit, but I couldn't make it work. I was left wondering if it's really necessary, since it adds some complexity. If it is needed, maybe we could find a way to only use it if it's present in the system. 

* Readme

The code depends on stdlib, so I mentioned it in the readme and added another example of use.

Hope those changes are useful. Sorry for not using a topic branch for that. Still learning to use pull requests. :-/