new rdflib using system install

added json-ld support in Description
set gitignore .pyc files
move static rdflib

using installed rdflib now, move static file out
remove rdflib static from tree
Add JSON graph types

add JSON graph types JSON-LD and RDF-JSON to the Description. Needed to
manually register the parsers in the startup sketch
make rdf-json the default representation and fix mimetype

using application/json for rdf-json (default)
and application/json+ld for JSON-LD
add graph types

support all types supported by rdflib 4.1
Merge pull request #3 from mjkoster/master

rdflib, JSON graphs, Object Serialization