[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] ecommerce onboarding misc improvements: tour, qty inc/dec, add placeholder for product desc bottom of add to cart button, add print button, cart icon fix for all themes, and last delivery module menu add to sale, so now both sale or warehouse delivery menu with access right stock.group_stock_manager and base.group_sale_manager, move from demo file to data file set for default one data as a delivery courier.