Ensured that SPARQL 1.1 JSON typed literals are parsed correctly.

The parsing code now supports both SPARQL 1.0 and 1.1 JSON results:

    {"type": "literal", "value": "S", "datatype": "D"}        # SPARQL 1.1 JSON
    {"type": "typed-literal", "value": "S", "datatype": "D"}  # SPARQL 1.0 JSON

See: http://www.w3.org/TR/sparql11-results-json/#select-encode-terms
See: http://www.w3.org/TR/rdf-sparql-json-res/#variable-binding-results