[banana] some refactoring + comments
[rdf] Parameterized return type for RDFReader functions.
[rdf] Parameterized return type for RDFWriter functions.
[rdf-test-suite] [Turtle|RdfXML]TestSuite no longer depend on Try
[rdf-test-suite] TurtleTestSuite no longer depend on Try
Merge branch 'master' of github.com:w3c/banana-rdf into topic/parameterized-return-type-io
[build] fix jsonld-java version dependency
Merge pull request #176 from w3c/topic/parameterized-return-type-io

This is good enough. I think it will help Antonio to make his changes.