An unofficial HTTP response status code is defined and used
internally in LibreOffice WebDAV ucp provider in order to
catch either the DAVException::DAV_HTTP_TIMEOUT state or the
DAVException::DAV_HTTP_CONNECT state.

Change-Id: Iec4927d18ace5384fed16a7ec2a2620dc8305c5b
Reviewed-on: https://gerrit.libreoffice.org/29757Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Giuseppe Castagno <giuseppe.castagno@acca-esse.eu>