Remove empty models.py files

common/djangoapps/enrollment/models.py

-"""
-A models.py is required to make this an app (until we move to Django 1.7)
-
-"""

lms/djangoapps/course_structure_api/models.py

-""" This file is intentionally empty. """

lms/djangoapps/debug/models.py

-# Create your models here.

lms/djangoapps/discussion_api/models.py

-"""
-A models.py is required to make this an app (until we move to Django 1.7)
-"""

lms/djangoapps/notifier_api/models.py

-# Django requires this module.

lms/djangoapps/staticbook/models.py

-# Create your models here.

lms/djangoapps/support/models.py

-"""
-Models for the student support app.
-"""

openedx/core/djangoapps/auth_exchange/models.py

-"""
-A models.py is required to make this an app (until we move to Django 1.7)
-"""