Added image metadata tests, fixed minor bug in servers service with metadata

Change-Id: Ia77280ce393619c7dc3f700a7fa4c45305a2defb
diff --git a/storm/tests/test_images.py b/storm/tests/test_images.py
index e11dc47..635dc62 100644
--- a/storm/tests/test_images.py
+++ b/storm/tests/test_images.py
@@ -35,7 +35,7 @@
         name = rand_name('image')
         resp, body = self.client.create_image(server['id'], name)
         image_id = self._parse_image_id(resp['location'])
-        self.client.wait_for_image_exists(image_id)
+        self.client.wait_for_image_resp_code(image_id, 200)
         self.client.wait_for_image_status(image_id, 'ACTIVE')
 
         #Verify the image was created correctly