Feature/filestorage sharenetworks update (#126)

* sfs: Add update for share networks

* sfs: Add acceptance tests for share network Update

* sfs: Add possiblity to update the network for share network

* sfs: Improve share network Update unit tests

* sfs: Improve share network Update acceptance tests
diff --git a/openstack/sharedfilesystems/v2/sharenetworks/urls.go b/openstack/sharedfilesystems/v2/sharenetworks/urls.go
index 9e2c8e9..6198c54 100644
--- a/openstack/sharedfilesystems/v2/sharenetworks/urls.go
+++ b/openstack/sharedfilesystems/v2/sharenetworks/urls.go
@@ -17,3 +17,7 @@
 func getURL(c *gophercloud.ServiceClient, id string) string {
 	return deleteURL(c, id)
 }
+
+func updateURL(c *gophercloud.ServiceClient, id string) string {
+	return deleteURL(c, id)
+}