MARMOTTA-325 : Deprecate APIs that make it difficult to extend formats

After deprecating both SPARQLGraphResultWriter, and the API methods that
rely on every type of query being applicable to a QueryResultWriter, the
code is substantially simpler, including removal of private methods in
SparqlWebService that are no longer required.

QueryResultWriter is only relevant to Tuple and Boolean results, so
hacking it to work with Graph results instead of using RDFHandler makes
it difficult to integrate with other API methods. Referencing RDFHandler
isn't even necessary in SparqlService if you only want to output to a
document, as
QueryResultIO.write(GraphQueryResult,RDFFormat,OutputStream) does the
resolution and handling automatically, as long as you can deal with
RDFHandlerException.
MARMOTTA-325 : Make io service more flexible wrt dynamic services

If parsers were loaded into the registry after startup, the current code
would not recognise them. In order to make it possible to do this for
marmotta, the io service needs to call the authoritative service
registry when asked about questions.

In addition, the list of accept types could contain duplicates if more
than one parser supports a given format, so filtering through a set.
MARMOTTA-325 : Add deprecated annotation on method that is not being
used but it still on the API
MARMOTTA-325 : Autogenerate the list of available response types

Uses the registries to generate the list of response types, which
previously included application/rdf+xml for tuple and boolean results
and will not include them after this update.