[IMP] crm: kanban customization
- stage model: add field holding the eventual specific legends for kanban
tates and star (priority) management
- crm.lead kanban: use kanban column using group_by_tooltip
- update data and demo data
[IMP] hr_recruitment: applicant kanban customization
- stage model: add field holding the eventual star (priority) management
+ updated applicant kanban view
[FIX] website_forum: fixes
    [FIX] website_forum: escape the tags from post at texttext rendering
    [FIX] website_forum: jquery is not already loaded
    [FIX] website_forum: use uid from session because WebsiteForum object has no attribute '_uid'
[FIX] fix bouncing issue in form view (web client)

the buttons edit and create have been ungrouped recently.  As a
side effect (of course), the bouncing effect in form view is broken.
This should hopefully fix the issue without introducing any other
problems :/
[FIX] crm: fixed bug in m2m between sales teams and stages introduced
when cleaning the models. The m2m table name is different when defined
in sales_team or in stages, leading to a quie strange behavior.
[FIX] website_forum: fix broken forum activation email due to the migration to the new API.

Next step: write tests. Hooray.
[FIX] hr_holidays: fix virtual remaining leaves computation.

Now only validated allocation requests are taken into account
when computing the number of virtual remaining leaves (leaves
+ pending leaves). This avoid creating allocation request to
have virtual remaining leaves artificially added.
[IMP] mass_mailing: add creation date in fields
to display it on list view + perform search on it.
[IMP] crm: added reason for loosing opportunities
[IMP] sale & sale_stock : removed 'Enable Invoicing Sales order lines' group from user setting and 'Generate invoices based on the sales order lines' group from sale setting.