mod_headers: Add 'Header note header-name note-name' to copy a headers

value into a note (so a CGI/Proxy header can be deleted and logged)

trunk patch: http://svn.apache.org/r1520908

Submitted by: covener
Reviewed by: jim, humbedooh


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1523271 13f79535-47bb-0310-9956-ffa450edef68