[FIX] account_anglo_saxon: correctly set the accounts for returns

The generated moves on a return should be the reverse of the outgoing move.
Fixes #1817, opw 604417
[FIX] mail: chatter read more/less expand first oe_msg_body_long/short in the first oe_msg_body

Otherwise, if the mail itself contains a oe_msg_body_long (because sent in the mail history), it will open that one
[FIX] stock/purchase: dates and currency rates

Use the currency rate of the purchase date instead of the one of at the reception time (opw 610430)
[FIX] hr_timesheet_sheet: avoid error when sort attendances

When an attendance line is edited, the tuple has no key 'name' which lead to a traceback.
Fixes #546
[FIX]stock_landed_costs: Fixed wrong costs on landed costs with many products
[REL] Odoo 8.0
[FIX] survey: display_mode is required if question type is simple_choice

Fixes #2461
[FIX] survey: typo in domain
[FIX] mrp_repair: pass context in product_id_change calls
[FIX] kanban: wrong condition to reset the dataset index

The dataset index should be reset either if the dataset is empty or the index is greater than the records size
[MERGE] forward port of branch 7.0 up to a218a9e
[MERGE] forward port of branch saas-3 up to 5bd0249
[FIX] website_sale: displayed price doesn't change for 'List View of Variants' customize template
[FIX] Packaging: Wndows: wrong handler used when logging to file
[FIX] web: form: quick create: name is now required to avoid creating records with a void name
[FIX] product: Even when the product template has more than 1 variant, the default_code is displayed.
[FIX] bus, im_chat, im_livechat : use correct session to rpc call, little refactoring of im_livechat js, and prepare js code for Odoo Support.
[FIX] base_gengo, website_gengo: groups on the gengo key.

Basically the admin group can read the gengo key. When adding website_gengo that adds the
website groups, the groups allowed to access the key are updated.

This is done because in base_gengo the website groups are not necesssarily defined. Website
is not a dependency of base_gengo.
Merge pull request #2550 from odoo-dev/8.0-fix-default_code-chm

[FIX] product: Even when the product template has more than 1 variant, the default_code is displayed.
Merge pull request #2543 from odoo-dev/8.0-fix-website_sale-list-variants-chm

[FIX] website_sale: displayed price doesn't change for 'List View of Variants' customize template