This task reflects an overhaul of the current SPARQLEndpoint implementation. The improvment should include proper content-negotiation, well know URLs (like /sparql), the implementation of "SPARQL Service Description"  to expose available features and "Graph Store Protocol"  as a basic CRUD interface (instead of loadRdf). check the subtasks for further details.. The implementation will be done in a non disruptive way to not interfer with clients of the current endpoint, all available options (e.g. auth parameter, infer parameter) will still be available.