[pep8] flake8 run for everything, fix items from this change

Signed-off-by: akoskaaa <akos.hochrein@prezi.com>

tests/unit/cli_test.py

@@ -8,7 +8,6 @@ from .. import unittest
 
 import docker
 import mock
-from six import StringIO
 
 from compose.cli import main
 from compose.cli.main import TopLevelCommand

tests/unit/config_test.py

@@ -234,7 +234,9 @@ class ExtendsTest(unittest.TestCase):
 
     def test_extends_validation(self):
         dictionary = {'extends': None}
-        load_config = lambda: config.make_service_dict('myweb', dictionary, working_dir='tests/fixtures/extends')
+
+        def load_config():
+            return config.make_service_dict('myweb', dictionary, working_dir='tests/fixtures/extends')
 
         self.assertRaisesRegexp(config.ConfigurationError, 'dictionary', load_config)
 

tests/unit/progress_stream_test.py

@@ -2,7 +2,6 @@ from __future__ import unicode_literals
 from __future__ import absolute_import
 from tests import unittest
 
-import mock
 from six import StringIO
 
 from compose import progress_stream