Halo: unregister settings obeservers

Change-Id: I57ec9b874c332bec8be2b3e3ed2505f6be53b79e
HALO: halo can save last position now

Change-Id: I5a608b02323ab9fdfa3922a3c9844e75c3a1ab09

fix

Change-Id: I00ced429cfcc90507b8cc14b228a74b8902e67e8