title: Django, multiple ModelAdmin for one Model
body: <p>I have Django 1.7.9 and python 2.7. I need multiple ModelAdmin 
  for one Model. One of them is standart and others with some 
  constant values. For example, I have model Item with foreign key 
  Categiries. I need model admin to create Item with constant 
  value for every category. How can I do it? Is it possible?)</p>