Added apache::mod::shib to configure Shibboleth Service Providers

Created a class apache::mod::shib to install, configure, and manage Shibboleth. Once this module is installed and configured and the site is registered as a Shibboleth Service Provider (SP) it should just be a matter of setting `authType shibboleth` in a HTTPS virtual host definition.

Currently only works for Debian and Ubuntu.

http://shibboleth.net/