Add a datatype for rdf:langString
JENA-818, JENA-816 : Rewrite sameValueAs.
rdf:langString registration test.
Correct javadoc.  Remove dead code.
Environment variable access.
Fix error message text
Fix dispach of opertations directly on the dataset URI.
Remove unused (old) classes.
JENA-818 : More tests for LiteralLabel.sameValueAs
Javadoc fix.
JENA-816: Changes for RDF 1.1

* Adapt tests
* Define LiteralLabel.isPlainLiteral to be true 
  for xsd:string in RDF 1.1
* PrintUtil.print(Node) does not output xsd:string.
More faithful version of LiteralImpl.isPlainLiteral.
Correct javadoc for isPlainLiteral.
JENA-816 : Suppress datatype xsd:string when out for RDF 1.1
JENA-816 : Argument compatibility for RDF 1.0 and RDF 1.1
Robust against RDF 1.0 and RDF 1.1
Some tidying up.
Armour ObjectFile contract and implementation.
Merge branch 'master' into hadoop-rdf