PEP fixes (not all yet)

InvenTree/InvenTree/helpers.py

@@ -1,18 +0,0 @@
-import inspect
-from enum import Enum
-
-
-class ChoiceEnum(Enum):
-    """ Helper class to provide enumerated choice values for integer fields
-    """
-    # http://blog.richard.do/index.php/2014/02/how-to-use-enums-for-django-field-choices/
-
-    @classmethod
-    def choices(cls):
-        # get all members of the class
-        members = inspect.getmembers(cls, lambda m: not(inspect.isroutine(m)))
-        # filter down to just properties
-        props = [m for m in members if not(m[0][:2] == '__')]
-        # format into django choice tuple
-        choices = tuple([(str(p[1].value), p[0]) for p in props])
-        return choices