removed mod_h2 directives which were experimental and should not support any...

removed mod_h2 directives which were experimental and should not support any longer, changed H2Direct to only be enabled by default when not using TLS, conf. to rfc7540

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1697446 13f79535-47bb-0310-9956-ffa450edef68