Instead of going up the stacktrace to find the module names of waffle
flags and switches, we manually pass the module __name__ whenever the
flag is created. This is similar to `logging.getLogger(__name__)`
standard behaviour.
As the waffle classes are used outside of edx-platform, we make the new
module_name argument an optional keyword argument. This will change once
we pull waffle_utils outside of edx-platform.
Note that the module name is normally only required to view the list of
existing waffle flags and switches. The module name should not be
necessary to verify if a flag is enabled. Thus, maybe it would make
sense to create a `add` class methor similar to:
class WaffleFlag:
@classmethod
def add(cls, namespace, flag, module):
instance = cls(namespace, flag)
cls._class_instances.add((instance, module))
