Update the SetFilter directive to work with Handlers instead of MIME-types.

This also updates the docs to reflect the change.
Submitted by:	Joshua Slive
Reviewed by:	Ryan Bloom


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@87028 13f79535-47bb-0310-9956-ffa450edef68