Fixes for CentOS

This pull request consists of two changes I needed to get the cpan module working on CentOS 6.4.

1: Some packages required approval to keep going.  I thus included an environent variable to tell cpan not to require approval.

2: The case statement on ::osfamily did not work as written.  I found when I wrapped the case expressions in single quotes it did work.  I couldn't find a grammar for the puppet language, but it seems like a reasonable change.

Tested on CentOS only.