Added support for RedHat based OSes

Hi 

I've added a support for RedHat based OSes e.g. Redhat, CentOS and Amazon linux and I'm hoping you'll be ok to accept this pull request (I've tried to make the changes discrete and easy to understand.

Changes:

* I've written the test suite using asserts based on the original module so it won't break anyone who is using it currently.
* It uses the same sane defaults for Debian and has been updated to handle ruby 1.9.x.
* Travis CI support has been added.
* All options have now be parameterized.
* Puppet-lint fixes.

Cheers

-Martin