bumped wai dependency to 2.0.0 in tests
Added two more function constructors for RDFLiteral

There are 'litRef' and 'litLangRef'
Merge branch 'master' of github.com:robstewart57/hsparql

Conflicts:
	Database/HSparql/QueryGenerator.hs
Removed RDFLiteral function constructors

They were based on obsolete types.
bumped version to 0.2.3