fix NoWriterForLangException: JSON-LD

Update to Jena 2.12.0 and use Jena's native support for jsonld-java,
which was recently added.

Fixes #161
Merge pull request #165 from spadgett/master

fix NoWriterForLangException: JSON-LD
Update testng.xml with better examples
Fixed some consistency problems with EARL results
Updated instructions for generated files
Removed usage of "NON-RDF" group, closes #166
Improve some of the docs
Refactoring to attempt to simplify some things
Updated to provide anchors from conformance documents.

Fixes #93