LUN-1832: fixed overwrite_url disappearance
LUN-1452: Removed unnecessary path updates on move.
Title paths are correctly updated on move for all cases
(in page post save signal):
* moved page becomes homepage
* moved page was homepage before save
* all descendants title paths are updated
Merge pull request #34 from pbs/fix_overwrite_url_disappearing

LUN-1832 Fix overwrite url disappearing