[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
[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
Merge branch '8.0' of https://github.com/odoo/odoo into 8.0_asset_invoice