Unittests

A bunch of tests. refs #14

There are a lot of commits, and later ones overwrite previous ones. If you think that I should compact this — I will :)

I made my best to limit the tests strictly to the public APIs. I had to do some evil (monkey-patch style) mocking to disable network-calls, as urlllib is hardcoded into sparqlwrapper.

I didn't invent a way to do a clean, but still meaningful test of `QueryResult.convert()` so I didn't right a test for it