[IMP] CRM Onboarding improvement
[IMP] sale_stock: warehouse_id field on sale order is now readonly, except in draft and sent states.
[IMP] accounting: modify writeoff_amount display in payment wizard
[FIX] website_mail & calendar: demo data break the layout of mail design
[FIX] website_mail: can't be edit the mail template, javascript must be added into the asset
[FIX] website: remove multi consecutive dropzone
[FIX] snippets: use the new API to define dropzone
Merge pull request #2547 from odoo-dev/master-fix-mass-mailling-snippet-chm

[FIX] website_mail: can't edit mail templates
[IMP] product: remove UoM constraint from product module and give it in stock and account module

Closes #2440