Added Puppet language syntax highlighting

Hello!

I have added Puppet language (http://puppetlabs.com/) to the library. I have checked the instructions in http://highlightjs.readthedocs.org/en/latest/language-contribution.html and everything should be fine.

Best regards,
José Molina

EDIT: here's a photo of the example I have created:
![pupet](https://cloud.githubusercontent.com/assets/2722756/4075989/0140b6e2-2eb6-11e4-8bf8-1311c386dcba.png)