Fix how mod_dav examines methods in the request -- use the method number

Fix how mod_dav examines methods in the request -- use the method number
from the request. To do this, we also need to register all of the new/custom
methods that mod_dav recognizes.

Note: this fixes a bug where a method (e.g. REPORT) would appear in a
Limit(Except) directive and Apache would register the method. The method
number in the request would then be something *other* than M_INVALID, which
threw off mod_dav's tests.

Submitted by: Sander Striker <striker@apache.org>

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@92764 13f79535-47bb-0310-9956-ffa450edef68