tasks #6627: Warn user on page leave if he has made changes

Change-Id: Ifb09adfda631d000a26162ab07eb011a7278d3cb
Merge commit 'refs/changes/03/2303/3' of ssh://gerrit.tuleap.net:29418/tuleap into HEAD

* ssh://gerrit.tuleap.net:29418/tuleap:
  tasks #6627: Warn user on page leave if he has made changes

Change-Id: I824124ce2345ba2190b4599d032ac513f14c10de
This is Tuleap 6.12.99.62

Change-Id: Ieea140fff2805bb8d66b3a9997388f48cf944cf8