Added check_field_is_empty decorator to cleaning.py.
This makes sure the cleaning checks are skipped when a field is empty. Note that Djanog will raise it's own ValidationError when a required field is empty before attempting to clean it.
Patch by: Lennard de Rijk
Reviewed by: to-be-reviewed.
include COPYINGinclude mox_test.pyinclude mox_test_helper.py