Merge r1560683 and r1581011 from trunk:

(mod/mod_proxy_express.xml)
It does more than just a ProxyPass, but also looks at the HOST header,
so this gives somewhat deeper insight into what the end result looks
like.

(mod/mod_proxy_connect.xml)
a comma leaked onto the page

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1598284 13f79535-47bb-0310-9956-ffa450edef68