This adds the ssl_verify_client parameter that
is passed down to the apache::vhost resource.
Without this being set, as of puppetlabs-apache 2.1.0,
the horizon_ca parameter will be ignored and you won't
get the CA/intermediate set in the vhost configuration. 
This was introduced a long long time ago which means we should
backport this or SSL is semi-broken when using this module.
(cherry picked from commit