Add support to set SSLCARevocationCheck on Apache 2.4

Apache 2.4 needs an additional SSLCARevocationCheck directive to enable
checking of a CRL, e.g. for a Puppet master vhost.

See https://github.com/puppetlabs/puppet/commit/b02af7e05d9b9a3bc23474933d8d7f6cd6191158
for more background
Merge pull request #866 from domcleal/ssl-crl-check

Add support to set SSLCARevocationCheck on Apache 2.4