Add *.local.wmftest.org wildcard, mapped to 127.0.0.1

This allows configuring Apache on MediaWiki-Vagrant to use name-based virtual
hosting to route requests to the correct application. Comparable to
<http://readme.localtest.me/>, except controlled by us and thus not likely to
be hijacked without anyone noticing.

Change-Id: Ifc752ac89bbfa1c793d37917b099b0c98dc38a5a