The URL exposed in the XML documents generated
by the server was wrong because instead of
using the original URL (from REQUEST_URI)
the rewritten query string (from QUERY_STRING)
was applied to the internal mUrl variable.
This patch also adds some tests for the
FCGI request, that handle most common
scenarios with bot rewritten and not
rewritten URLs.
QgsFcgiServerRequest is now exposed to
Python mainly for testability purposes.
