Merge r1457437, r1457520 from trunk:

Expression parser: Add the ability to base64 encode and base64 decode
strings within the parser.


Remove the comment, this is done.

Submitted by: minfrin
Reviewed/backported by: jim


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1467969 13f79535-47bb-0310-9956-ffa450edef68