more error types; RequestOptsBuilder error fixes
diff --git a/openstack/compute/v2/servers/requests.go b/openstack/compute/v2/servers/requests.go
index 06db312..c6d3a8e 100644
--- a/openstack/compute/v2/servers/requests.go
+++ b/openstack/compute/v2/servers/requests.go
@@ -759,7 +759,7 @@
 // Metadatum requests the key-value pair with the given key for the given server ID.
 func Metadatum(client *gophercloud.ServiceClient, id, key string) GetMetadatumResult {
 	var res GetMetadatumResult
-	_, res.Err = client.Request("GET", metadatumURL(client, id, key), gophercloud.RequestOpts{
+	_, res.Err = client.Request("GET", metadatumURL(client, id, key), &gophercloud.RequestOpts{
 		JSONResponse: &res.Body,
 	})
 	return res