Jena fuseki support (SPARQL 1.1)

These commits intend to make r43ples work with the jena fuseki triplestore server. Although most operations already work, these changes are to be considered "quick&dirty". The merging code was not touched at all and will surely not work on jena fuseki.
Since this code state is unstable (Virtuoso should also not work anymore), it should not be merged with master but could go in a new feature branch to be able to go on from these changes. If anyone will create this new branch upstream I will alter this merge request (if possible) or create a new one.

related to Ticket #32