Added nm-tray.conf to xdg-Lubuntu so nm-connection-editor is default. Bump standards, apply new debhelper and compat norms

Summary: Added nm-tray to xdg-Lubuntu with nm-connection editor

Test Plan: check if nm-tray uses nm-connection-editor instead of nmtui

Reviewers: wxl

Reviewed By: wxl

Subscribers: kc2bez, wxl

Differential Revision: https://phab.lubuntu.me/D82