Ensure StorageURL ends in a slash (#183)

* Ensure StorageURL ends in a slash

* Use NormalizeURL instead of HasSuffix

* Go back to a one-line import
diff --git a/openstack/objectstorage/v1/swauth/requests.go b/openstack/objectstorage/v1/swauth/requests.go
index ce4bf9a..e8589ae 100644
--- a/openstack/objectstorage/v1/swauth/requests.go
+++ b/openstack/objectstorage/v1/swauth/requests.go
@@ -61,7 +61,7 @@
 
 	swiftClient := &gophercloud.ServiceClient{
 		ProviderClient: pc,
-		Endpoint:       auth.StorageURL,
+		Endpoint:       gophercloud.NormalizeURL(auth.StorageURL),
 	}
 
 	swiftClient.TokenID = auth.Token