Fix tempest lib import in API tests

Change Ic2d4cea4f11222fc7b45eb378cfc32974c1be9b6
removed the service_client module and replaced it
with rest_client. This updates our code to reflect
that.

Change-Id: I5f6b0de632703eac6b6f05ae48c44d511f1fda5e
Closes-Bug: #1554362
diff --git a/neutron/tests/tempest/services/network/json/network_client.py b/neutron/tests/tempest/services/network/json/network_client.py
index 697711b..0795d58 100644
--- a/neutron/tests/tempest/services/network/json/network_client.py
+++ b/neutron/tests/tempest/services/network/json/network_client.py
@@ -14,13 +14,13 @@
 
 from oslo_serialization import jsonutils as json
 from six.moves.urllib import parse as urlparse
-from tempest.common import service_client
+from tempest.lib.common import rest_client as service_client
 from tempest.lib import exceptions as lib_exc
 
 from neutron.tests.tempest import exceptions
 
 
-class NetworkClientJSON(service_client.ServiceClient):
+class NetworkClientJSON(service_client.RestClient):
 
     """
     Tempest REST client for Neutron. Uses v2 of the Neutron API, since the