Fix flake8: E402 module level import not at top of file

Also sort imports.

Author: blueyed

pytest_django/plugin.py

@@ -4,12 +4,13 @@
 test database and provides some useful text fixtures.
 """
 
-import os
-
 import contextlib
+import os
+import sys
+import types
 
+import py
 import pytest
-import types
 
 from .django_compat import is_django_unittest
 from .fixtures import (_django_db_setup, _live_server_helper, admin_client,
@@ -62,9 +63,6 @@ def pytest_addoption(parser):
                   'Python path.',
                   default=True)
 
-import py
-import sys
-
 
 def _exists(path, ignore=EnvironmentError):
     try: