Quick fix to allow selecting method to query

It's really annoying that we have so many patches that go unused for 2
reasons:
a) We're not using the query construction anymore (IIRC it was too
slow/inflexible)
b) The Virtuoso they were added for was less compliant than the one
we're using

However for the moment there are also some patches that we aren't
compatible with (for example because of monkey patching rdf.rb), so we
can't just switch to the official version of sparql-client.