Propagate T instance to makeSubject.
Add new helper method for PGB construction.
Add tests for new pgb helpers.
Merge pull request #46 from artemkozlov/master

Propagate T instance to makeSubject.
some documentation
fix documentation
fix documentation
fix documentation
fix documentation
fix documentation
fix documentation
Merge branch 'master' of github.com:w3c/banana-rdf into ldp