[FIX] web_tip: handles `content changed` event in forms; minor fixes

* eval tip on form content changes
* prevent multiple tip trigerring in some cases
* use scrollTo jquery plugin
[ADD] website: new blog demo snippets

(cherry picked from commit 6c6df546eb5a99d00d62fc6b497b4b861431423e)
(closes #2631)
[ADD] web: add widget button of Active/Deactive user.
[IMP] Improve user form view