Fix issue with sqlite not storing literals properly.
Parameters are encoded strings, not Unicode.
assertIsNone was introduced in Python3.1. Its use here should be replaced by
self.assertEquals(o.language, None)
to allow Python 2.X tests to run.
Propagate the fix to the py3compat version.
Merge pull request #5 from editorsnotes/master

SQL backends not storing literals properly.
Remove junk.
Fix tests.
Ensure db param is quoted. Correct self.bind query string composition. Finesse various infelicities.
Require rdflib 4.0 for installation.
Merge commit '119e7840ded581d20c61d20b968be86a61aaeec2'