Add support for Red Hat family systems

Variables and tasks for running this role on Red Hat derived systems. I've
tried to update the README to mention any requirements and changed the mention
of only supporting Debian.
Add EL to supported platforms

This changeset should work with EL 5 and 6 so 'all' enabled.
Merge pull request #4 from goetzk/Support-RedHat-systems

Add support for Red Hat family systems