Fix some pep8 errors, update tox.ini

Fixed E731, W503 and I201 pep8 errors.

Added flake8-import-order to test-requirements.txt to avoid
an "unknown option 'import-order-style' ignored" warning.

Removed {posargs} from flake8 invocation so it can be called
such as 'tox -e pep8 HEAD~1' in order to only run on files
changed in the top commit.

Removed py34, py27 and pypy from the tox.ini envlist since
there are no unit tests, and tox reports it skipped all tests.

Change-Id: I574cafe074befa59aaee44b092b011e27f5f4211
diff --git a/neutron_tempest_plugin/api/test_routers.py b/neutron_tempest_plugin/api/test_routers.py
index bc657e0..d5d2e04 100644
--- a/neutron_tempest_plugin/api/test_routers.py
+++ b/neutron_tempest_plugin/api/test_routers.py
@@ -159,9 +159,12 @@
         # Add router interface with subnet id
         router = self._create_router(data_utils.rand_name('router'), True)
         intf = self.create_router_interface(router['id'], subnet['id'])
-        status_active = lambda: self.client.show_port(
-            intf['port_id'])['port']['status'] == 'ACTIVE'
-        utils.wait_until_true(status_active, exception=AssertionError)
+
+        def _status_active():
+            return self.client.show_port(
+                intf['port_id'])['port']['status'] == 'ACTIVE'
+
+        utils.wait_until_true(_status_active, exception=AssertionError)
 
     @decorators.idempotent_id('c86ac3a8-50bd-4b00-a6b8-62af84a0765c')
     @tutils.requires_ext(extension='extraroute', service='network')