Fix import order to comply with import ordering rules.

Fixes pep8 failures TEMPEST N306 and N301.

Change-Id: I87d6ef4058170da73ff64d4e4a4caf43f8a18046
diff --git a/tempest/services/compute/json/keypairs_client.py b/tempest/services/compute/json/keypairs_client.py
index 553936c..90b2096 100644
--- a/tempest/services/compute/json/keypairs_client.py
+++ b/tempest/services/compute/json/keypairs_client.py
@@ -15,9 +15,10 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-from tempest.common.rest_client import RestClient
 import json
 
+from tempest.common.rest_client import RestClient
+
 
 class KeyPairsClientJSON(RestClient):