SES-1694 : Add namespace logging to SPARQL XML Writer
SES-1694 : Add qname support to QueryResultWriters from BaseServlet
SES-1720 : Add writer settings to allow backwards compatibility with
RDF-1.0 where necessary

Both Plain Literals and Language Literals will be represented
differently internally from RDF-1.1.

Plain Literals will now always be typed and will always have xsd:string
as their datatype

Language Literals will now always be typed and will always have
rdf:langString as their datatype

The settings default to false, to allow backwards compatibility without
users having to switch it on everytime in the future.

These settings do not require any changes to the Literal interface,
other than to indicate in the contract that datatype will always be set
in future, and if and only if the datatype is rdf:langString, the
language will be set
SES-1720 : Add RDF-1.0 compatibility mode to SPARQL XML Writer

The workbench requires that literals not have datatypes in order for
them to be rendered correctly. This enables this backwards compatability
for the XSLT scripts in future.

The feature is off by default, so the rdf:langString and xsd:string will
still be written if they are available in other usecases
SES-1694 : Turn on RDF-1.0 compatibility in workbench to work with XSLT
stylesheets
SES-1720 : Only add rdf:langString if there was a datatype on the
literal

In future RDF-1.1 parsers will be adding rdf:langString automatically,
but for now they do not appear, so not adding them inside of the SPARQL
XML Writer