[form] fix validation error handling * type when possible ValidationError raised by the edit controller * don't rely on repository to check required field * turn css class used for field error message to errorMsg to avoid confusion with the error class added to input * fix css when errors are added by the form renderer * fix form renderer to add the error message

#!/usr/bin/env python
from cubicweb.cwctl import run
import sys
run(sys.argv[1:])