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

Change-Id: Ia77280ce393619c7dc3f700a7fa4c45305a2defb
diff --git a/storm/services/nova/json/servers_client.py b/storm/services/nova/json/servers_client.py
index 6bad76e..e65173f 100644
--- a/storm/services/nova/json/servers_client.py
+++ b/storm/services/nova/json/servers_client.py
@@ -285,7 +285,7 @@
 
     def set_server_metadata_item(self, server_id, key, meta):
         post_body = json.dumps({'meta': meta})
-        resp, body = self.client.put('servers/%s/metdata/%s' %
+        resp, body = self.client.put('servers/%s/metadata/%s' %
                                     (str(server_id), key),
                                     post_body, self.headers)
         body = json.loads(body)