ImageService v2: Fixing Create Properties (#264)

* Fix Creating Image Properties

The combination of JSON tags were not rendering the JSON body
correctly and causing a 400 error by the API.

* ImageService v2 Acceptance Tests

* unit tests
diff --git a/openstack/imageservice/v2/images/testing/fixtures.go b/openstack/imageservice/v2/images/testing/fixtures.go
index 1754407..10a87b4 100644
--- a/openstack/imageservice/v2/images/testing/fixtures.go
+++ b/openstack/imageservice/v2/images/testing/fixtures.go
@@ -158,6 +158,7 @@
 		th.TestJSONRequest(t, r, `{
 			"id": "e7db3b45-8db7-47ad-8109-3fb55c2c24fd",
 			"name": "Ubuntu 12.10",
+			"architecture": "x86_64",
 			"tags": [
 				"ubuntu",
 				"quantal"