Add missing exceptions import

security_groups_client.py and security_groups_client.py are using the
"exceptions" module, but it was not imported.

Change-Id: Ib39e28ad7a4a49833ac9a4090da5b783e3075a03
diff --git a/tempest/services/compute/json/security_groups_client.py b/tempest/services/compute/json/security_groups_client.py
index 7f430d8..1dc11c4 100644
--- a/tempest/services/compute/json/security_groups_client.py
+++ b/tempest/services/compute/json/security_groups_client.py
@@ -19,6 +19,7 @@
 import urllib
 
 from tempest.common.rest_client import RestClient
+from tempest import exceptions
 
 
 class SecurityGroupsClientJSON(RestClient):
diff --git a/tempest/services/compute/xml/security_groups_client.py b/tempest/services/compute/xml/security_groups_client.py
index 7db60a1..10f1a42 100644
--- a/tempest/services/compute/xml/security_groups_client.py
+++ b/tempest/services/compute/xml/security_groups_client.py
@@ -19,6 +19,7 @@
 import urllib
 
 from tempest.common.rest_client import RestClientXML
+from tempest import exceptions
 from tempest.services.compute.xml.common import Document
 from tempest.services.compute.xml.common import Element
 from tempest.services.compute.xml.common import Text