Merge pull request #4154 from edx/benmcmorran/remove-datetuple

Removes DateTuple field type

cms/lib/xblock/mixin.py

-"""
-Mixin defining common Studio functionality
-"""
-
-import datetime
-
-from xblock.fields import Scope, Field, Integer, XBlockMixin
-
-
-class DateTuple(Field):
-    """
-    Field that stores datetime objects as time tuples
-    """
-    def from_json(self, value):
-        return datetime.datetime(*value[0:6])
-
-    def to_json(self, value):
-        if value is None:
-            return None
-
-        return list(value.timetuple())