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/acceptance/clients/clients.go b/acceptance/clients/clients.go
index f07754f..8bf4aa3 100644
--- a/acceptance/clients/clients.go
+++ b/acceptance/clients/clients.go
@@ -266,6 +266,25 @@
 	return openstack.NewIdentityV3(client, gophercloud.EndpointOpts{})
 }
 
+// NewImageServiceV2Client returns a *ServiceClient for making calls to the
+// OpenStack Image v2 API. An error will be returned if authentication or
+// client creation was not possible.
+func NewImageServiceV2Client() (*gophercloud.ServiceClient, error) {
+	ao, err := openstack.AuthOptionsFromEnv()
+	if err != nil {
+		return nil, err
+	}
+
+	client, err := openstack.AuthenticatedClient(ao)
+	if err != nil {
+		return nil, err
+	}
+
+	return openstack.NewImageServiceV2(client, gophercloud.EndpointOpts{
+		Region: os.Getenv("OS_REGION_NAME"),
+	})
+}
+
 // NewNetworkV2Client returns a *ServiceClient for making calls to the
 // OpenStack Networking v2 API. An error will be returned if authentication
 // or client creation was not possible.