Adding RHEL6 to the list of supported OS families.

RHEL6 uses the same directory for limit files.  Added RedHat to the list of acceptable OS families.
Merge pull request #3 from robsweet/master

Added RedHat to the list of acceptable OS families
Make sure files for limits.d end in .conf

This module was properly creating limits files but PAM wasn't using them
because they didn't end in .conf.  This change ensures that the created file
ends in .conf.
Merge pull request #4 from robsweet/master

Make sure created limits files end in .conf
Version 2.0.1