[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)
[IMP] base_action_rule: allow using the CharDomain widget
to set the filter and pre-update filter. Using ir.filters is still
possible, but is not the only way anymore of setting the domains
used in the base action rules.
[IMP] crm, project, hr_recruitment: star (priority) management: less possible values, too much stars are too much tears !
[HR] clean model in a changes the hr_applicant model in add the _content_serach method and hr_contract models in add the xml id on the serach and remove _resolve_department_id_from_context method in hr_recruitment model.and add a method _broadcast_welcome hr_recuriemnt models.