* [8.0][mass_mailing] some fixes
* [FIX] rename wrong mailing_type field and add missing fields when creating a mass mailing from the composer
* [FIX] coerce tooltip to an unicode string to avoid a json crash when locale produces a non unicode string for strftime(%B)
* [FIX] repair wrong sql statement computing statistics
[FIX] product: don't display 'create and edit' option on many2many_tag to create variant on product_template. The quick create is confusing for users
[ADD] doc: new documentation, with training tutorials, and new scaffolding
[IMP] doc/howtos/backend: use scaffolding and adapt text and code accordingly
Merge pull request #1776 from acsone/8.0-jne-mass_mailing-improvements

[FIX] Mass mailing: fixed statistics computation + summary graph tooltips (using ustr) + values of the mass mailing when creating it from the mail composer wizard. Courtesy of Acsone.
[IMP] doc/howtos/backend: add a small section on how to start the server
[FIX] mail: do not send email at module installation
[FIX] point_of_sale: the category list now uses less space when the categories don't have pictures, freeing some screen space on tablets
[FIX] model: prevent exporting column ID of non ordinary tables

This makes no sense and can generate errors if you try to purge
ir.model.data of not existing records.
[IMP] doc/howtos/backend: finalize section on translations, and other small fixes
[IMP] doc/howtos/backend: fix calendar example
[IMP] doc/howtos/backend: fix condition in workflow
Merge pull request #1970 from odoo-dev/8.0-fix-dont-display-edit-product-many2many-chm

[FIX] product: don't display 'create and edit' option on many2many_tag
[FIX] website.layout hreflangs

- First line is not correct due to url_for() refactoring's leftover
- href's should be full urls with domain name
- Use short language for hreflang if possible
[FIX] Missing part of the revision 5f6fc473
[FIX] allow `--log-db` to connect to another postgresql server than the one setted in config
[IMP] doc/howtos/backend: usage of odoo.py
[FIX] website_event: allow everybody to ready event.type. Else a user who is not public, not portal and not event user or event manager cannot read the event.
[FIX] redirect /page/website.xyz --> /page/xyz. Currently 302 but fme will convert to 301
[FIX] website_forum: fixed setting an answer as valid / invalid. The change
in the behavior of browse records due to the new API introduced a wrong
behavior, now fixed.