Switch from RDF::NS to RDF::NS::Curated

[phochste]

To keep the code tests stable (RDF::NS is crowd sourced).

Check also URI::NamespaceMap for providing holding a collection of namespaces

[kjetilk]

Not just for tests, but for code that needs to be stable over a long time. :-)

I've committed hydra to master now, and I have a branch with a scalar qname function.

I get weird results when trying to generalize it to array context, but i have opened a bug for it on myself:
perlrdf/p5-rdf-ns-curated#3

[kjetilk]

I thought this was going to be trivial now that RDF::NS::Curated has a qname method, so I did that in https://github.com/phochste/RDF-LDF/tree/feature-curated but tests are failing. I can't commit time to that right now, but I figured I'd push anyway.