Feature/filestorage securityservices delete (#133)

* sfs: Add support for security services Delete

* sfs: Add acceptance tests for security service Delete
diff --git a/openstack/sharedfilesystems/v2/securityservices/urls.go b/openstack/sharedfilesystems/v2/securityservices/urls.go
index ba0ae6d..5cbdd17 100644
--- a/openstack/sharedfilesystems/v2/securityservices/urls.go
+++ b/openstack/sharedfilesystems/v2/securityservices/urls.go
@@ -5,3 +5,7 @@
 func createURL(c *gophercloud.ServiceClient) string {
 	return c.ServiceURL("security-services")
 }
+
+func deleteURL(c *gophercloud.ServiceClient, id string) string {
+	return c.ServiceURL("security-services", id)
+}