Update timezone function width dbus's new function

tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/d1c364af66c647b184b35f72d3d87e46/

tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/7f05472539984dcb92ebb26c9c462d2a/

tower: https://tower.im/projects/8f19f0bf0e754f0b82ef2c24bc230973/todos/42bb94f42ebe41aa858cca0fc2ed2a8c/

Change-Id: I419da05f0d47690a5d3da3336558b3f3154376e5