Fixed RHEL issues with init.pp and made auth-passwd template work.

I couldn't get the module to actually run because the package was defined with the same name several times in RHEL. Updated the mailpackages so that its called once. I wrote the template for auth-passwd incorrectly so this has been updated as well. All tested in CentOS 6.5. 

** ensure_packages([$mailpackages]) requires puppet/stdlib be installed.