enhancement: support comments in sparql queries

[nvdk]

A common thing for larger queries is to comment parts of it using the turtle comment syntax

# some comment here

Currently this will raise a parsing error in the mu-authorization, which is often hard to debug as validating the query via a service as http://sparql.org/query-validator.html will yield that it's valid query.

A way to support this could be just stripping these out with a regex before parsing.