[COOK-2893] Improve mod_auth_openid recipe with guards and idempotency

Signed-off-by: Seth Vargo <sethvargo@gmail.com>
Fix documentation for node['apache']['default_site_enabled']

The README indicates the default value for node['apache']['default_site_enabled'] is true on RedHat systems, but it is always false.
Update path to templates/default/mods/ssl.conf.erb

Update the README.md with the new path to the SSL conf template
Merge branch 'master' of github.com:opscode-cookbooks/apache2