Using the digest Authentication scheme for proxy authentication, authorization

never succeeds because mod_digest always looks at the Authorization header,
never at the Proxy-Authorization header.

Also, the scheme in the auth header is compared to "Digest" using a case-
sensitive comparison, instead of a case-insensitive comparison.

PR:		1599
Submitted by:	Ronald Tschalaer <Ronald.Tschalaer@psi.ch>
Reviewed by:	Dean Gaudet, Jim Jagielski


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@79814 13f79535-47bb-0310-9956-ffa450edef68