Allow for extra dynamic fields for the create form
Also some minor cleanups, such as making base.Logic inherit from
object, as per the style guide.
Patch by: Sverre Rabbelier
from django.dispatch import Signal
class_prepared = Signal(providing_args=["class"])
pre_init = Signal(providing_args=["instance", "args", "kwargs"])
post_init = Signal(providing_args=["instance"])
pre_save = Signal(providing_args=["instance", "raw"])
post_save = Signal(providing_args=["instance", "raw", "created"])
pre_delete = Signal(providing_args=["instance"])
post_delete = Signal(providing_args=["instance"])
post_syncdb = Signal(providing_args=["class", "app", "created_models", "verbosity", "interactive"])