Merged /httpd/httpd/trunk:r1864924,1868506,1868654,1868927 from trunk
*) mod_md: Adding the several new features. The module offers an implementation of OCSP Stapling that can replace fully or for a limited set of domains the existing one from mod_ssl. OCSP handling is part of mod_md's monitoring and message notifications. If can be used for sites that do not have ACME certificates. The url for a CTLog Monitor can be configured. It is used in the server-status to link to the external status page of a certicate. The MDMessageCmd is called with argument "installed" when a new certificate has been activated on server restart/reload. This allows for processing of the new certificate, for example to applications that require it in different locations or formats.