Fix module's import order

Made corrections in import order for built-in, third party and
project specific modules as per OpenStack import standards [1].

[1] http://docs.openstack.org/developer/hacking/#import-order-template

Change-Id: I899deefd6ee4732d6c0afd17a5afbe42b0fa37ba

neutron/tests/functional/scheduler/test_dhcp_agent_scheduler.py

@@ -14,6 +14,8 @@
 #    under the License.
 
 import collections
+from operator import attrgetter
+
 import six
 import testscenarios
 
@@ -24,7 +26,6 @@ from neutron.db import common_db_mixin
 from neutron.scheduler import dhcp_agent_scheduler
 from neutron.tests.unit.scheduler import (test_dhcp_agent_scheduler as
                                           test_dhcp_sch)
-from operator import attrgetter
 
 # Required to generate tests from scenarios. Not compatible with nose.
 load_tests = testscenarios.load_tests_apply_scenarios

neutron/tests/functional/scheduler/test_l3_agent_scheduler.py

@@ -15,6 +15,7 @@
 
 import collections
 import random
+
 import testscenarios
 
 from neutron import context