Nesting applications can cause name collision in admin

[Chris Dickinson]

Installing two applications (one nested in a module) with the same name and model names will cause a name collision between the models in admin.

for example:

INSTALLED_APPS = (

'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.sites',
'django.contrib.admin',
'rhs',
'nest.lhs', #comment this app to make the application work again
'lhs',

)

where rhs, lhs, and nest.lhs all contain a models.py with the same model name, and functionally identical admin.py files.

[James Bennett]

Duplicate of #3591.