hook mimetype-forcing into fixup/LAST. This leads to consistent

behaviour (server context vs. directory context), overrides all statically
configured mime types and doesn't clobber multiviews any longer.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@100913 13f79535-47bb-0310-9956-ffa450edef68