Fix import order to comply with import ordering rules.

Fixes pep8 failures TEMPEST N306 and N301.

Change-Id: I87d6ef4058170da73ff64d4e4a4caf43f8a18046
diff --git a/tempest/tests/boto/test_ec2_keys.py b/tempest/tests/boto/test_ec2_keys.py
index 79d0b2b..b9e5508 100644
--- a/tempest/tests/boto/test_ec2_keys.py
+++ b/tempest/tests/boto/test_ec2_keys.py
@@ -15,12 +15,12 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-
 from nose.plugins.attrib import attr
 import unittest2 as unittest
-from tempest.testboto import BotoTestCase
+
 from tempest.common.utils.data_utils import rand_name
 from tempest import openstack
+from tempest.testboto import BotoTestCase
 
 
 def compare_key_pairs(a, b):