OCSADV-27: VoTableClient

This is a small PR containing VoTableClient. It uses the http commons client library to produce a method that returns a Future[CatalogProblem \/ ParsedVoResource] after making a call to one of the Gemini catalogs

A few rawtype warnings were removed as well
My tests show that with only one running (as it is now where mko works but cpo doesn't) things work ok, but the documentation of `firstCompletedOf` was a bit unclear in that respect