script_utils.py (parseInputs): "un"require/deprecate input argument `session'.

Function omero.util.script_utils.parseInputs requires the session as one of the
of the input arguments. However, this argument was actually never used by the
function. Deprecate by defaulting to None.
Merge pull request #2438 from carandraug/develop

script_utils.py (parseInputs): "un"require/deprecate input argument `session'.