Merge branch 'bugfix/231-aleksis-core-models-custommenu-doesnotexist' into 'master'

Resolve "aleksis.core.models.CustomMenu.DoesNotExist: CustomMenu matching query does not exist."

Closes #231

See merge request AlekSIS!236

aleksis/core/models.py

@@ -536,12 +536,6 @@ class CustomMenu(ExtensibleModel):
     def __str__(self):
         return self.name if self.name != "" else self.id
 
-    @classmethod
-    def maintain_default_data(cls):
-        menus = ["footer"]
-        for menu in menus:
-            cls.get_default(menu)
-
     @classmethod
     def get_default(cls, name):
         menu, _ = cls.objects.get_or_create(id=name, defaults={"name": name})