cyclades: Fix broken tests from commit #c172f4a

Commit #c172f4a used the "size" attribute of images. This commit
fixes mocked images of tests to contain this attribute.

snf-cyclades-app/synnefo/api/tests/servers.py

@@ -324,6 +324,7 @@ fixed_image.return_value = {'location': 'pithos://foo',
                             'checksum': '1234',
                             "id": 1,
                             "name": "test_image",
+                            "size": "41242",
                             'disk_format': 'diskdump'}