set image api to 1 for functional tests

devstack now defaults to image api v2, but osc does not support
v2 image create. set the functional tests to use v1 for now
to unwedge the gate.

Closes-Bug: #1496337
Change-Id: Ia02ed761446b8de52c932a424b9c423691ebcceb

functional/tests/image/v1/test_image.py

@@ -10,6 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import os
 import uuid
 
 from functional.common import test
@@ -25,6 +26,7 @@ class ImageTests(test.TestCase):
 
     @classmethod
     def setUpClass(cls):
+        os.environ['OS_IMAGE_API_VERSION'] = '1'
         opts = cls.get_show_opts(cls.FIELDS)
         raw_output = cls.openstack('image create ' + cls.NAME + opts)
         expected = cls.NAME + '\n'