Fix import line

[alexgleason]

Without this I get the error ImportError: No module named 'models'. It needs a period in front of .models so it imports models.py from the current app.

Full traceback:

[pedsnet vagrant]$ ./manage.py makemigrations
Traceback (most recent call last):
  File "./manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/vagrant/.virtualenvs/pedsnet/lib/python3.4/site-packages/django/core/management/__init__.py", line 354, in execute_from_command_line
    utility.execute()
  File "/home/vagrant/.virtualenvs/pedsnet/lib/python3.4/site-packages/django/core/management/__init__.py", line 328, in execute
    django.setup()
  File "/home/vagrant/.virtualenvs/pedsnet/lib/python3.4/site-packages/django/__init__.py", line 18, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/home/vagrant/.virtualenvs/pedsnet/lib/python3.4/site-packages/django/apps/registry.py", line 115, in populate
    app_config.ready()
  File "/home/vagrant/.virtualenvs/pedsnet/lib/python3.4/site-packages/django/contrib/admin/apps.py", line 22, in ready
    self.module.autodiscover()
  File "/home/vagrant/.virtualenvs/pedsnet/lib/python3.4/site-packages/django/contrib/admin/__init__.py", line 24, in autodiscover
    autodiscover_modules('admin', register_to=site)
  File "/home/vagrant/.virtualenvs/pedsnet/lib/python3.4/site-packages/django/utils/module_loading.py", line 74, in autodiscover_modules
    import_module('%s.%s' % (app_config.name, module_to_search))
  File "/home/vagrant/.virtualenvs/pedsnet/lib/python3.4/importlib/__init__.py", line 109, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 2254, in _gcd_import
  File "<frozen importlib._bootstrap>", line 2237, in _find_and_load
  File "<frozen importlib._bootstrap>", line 2226, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 1200, in _load_unlocked
  File "<frozen importlib._bootstrap>", line 1129, in _exec
  File "<frozen importlib._bootstrap>", line 1471, in exec_module
  File "<frozen importlib._bootstrap>", line 321, in _call_with_frames_removed
  File "/vagrant/pedsnet/wagtail_blog/admin.py", line 4, in <module>
    from models import BlogPage, BlogIndexPage
ImportError: No module named 'models'