psycopg2 version behind when using Docker and Postgres

When attempting to boot the NSoT Docker image with `ENV['DB_ENGINE']` = `django.db.backends.postgresql`, the container fails to start with:

```
ImproperlyConfigured: psycopg2_version 2.5.4 or newer is required; you have 2.4.5 (dt dec mx pq3 ext)
Traceback (most recent call last):
File "/usr/local/lib/python2.7/dist-packages/logan/runner.py", line 116, in settings_callback
'settings': settings,
File "/usr/local/lib/python2.7/dist-packages/nsot/util/core.py", line 341, in initialize_app
connections['default'].allow_thread_sharing = True
File "/usr/local/lib/python2.7/dist-packages/django/db/utils.py", line 211, in __getitem__
backend = load_backend(db['ENGINE'])
File "/usr/local/lib/python2.7/dist-packages/django/db/utils.py", line 115, in load_backend
return import_module('%s.base' % backend_name)
File "/usr/lib/python2.7/importlib/__init__.py", line 37, in import_module
__import__(name)
File "/usr/local/lib/python2.7/dist-packages/django/db/backends/postgresql/base.py", line 36, in
raise ImproperlyConfigured("psycopg2_version 2.5.4 or newer is required; you have %s" % psycopg2.__version__)
```

At first, I thought this may be due to the fact that `nsot/nsot:latest` does not appear to have been bumped with the release of 1.4.5, but manually building the image with that version seems to have the same problem.