Feature/filestorage sharenetworks list (#124)

* sfs: Add list for share networks

* sfs: Add acceptance tests for share network List

* sfs: Add more fields for filtering List requests

* sfs: Add pagination for share network List

* sfs: Change pagination to use MarkerPage

* sfs: Add acceptance tests for share network pagination
diff --git a/openstack/sharedfilesystems/v2/sharenetworks/urls.go b/openstack/sharedfilesystems/v2/sharenetworks/urls.go
index 7cd6c73..464c17a 100644
--- a/openstack/sharedfilesystems/v2/sharenetworks/urls.go
+++ b/openstack/sharedfilesystems/v2/sharenetworks/urls.go
@@ -9,3 +9,7 @@
 func deleteURL(c *gophercloud.ServiceClient, id string) string {
 	return c.ServiceURL("share-networks", id)
 }
+
+func listDetailURL(c *gophercloud.ServiceClient) string {
+	return c.ServiceURL("share-networks", "detail")
+}