[FIX] data dir when home is not a directory

Use site data dir instead of user data dir when user's home is not a directory.
Like system users created with /dev/null as home.

Stricter than before.
handle missing JS files with a console log
[FIX] product: some fields on the product template readonly when my product doesn't have any variant
[FIX] website_sale: can't click on confirm order in mobile view
[FIX] point_of_sale: On product form : push on button 'Set a Custom Ean' on tab information raise an exception => Use a record action and clean python files
[FIX] website: the media video create by the media editor is not display in firefox. change the css to display the video and add z-index to the div for edit mode
[FIX] website_sale: everytime you want to change both billing & delivery address, any change creates duplicates in the backend
[FIX] product_visible_discount: no crash when no pricelist passed or product without company

Fixes an error introduced in f6fb2b6
[MERGE] Forward-port 7.0 up to 2493395
[MERGE] Forward-port saas-3 up to b6acdc4
[IMP] openerp.api: improve documentation
[FIX] payment_paypal: paypal IPN, receiver_id is not always passed

The method  _paypal_form_get_invalid_parameters checks that the params passed by the paypal feedback coroborate with the transaction requested by Odoo.

It looks like the 'receiver_id' is not always passed by the paypal feedback. Therefore, we check this param only if it is available in the paypal feeback.

This issue had as side-effect to not validate the paypal transaction, which remained 'draft' permanently.
[FIX] payment*: add the customer state to payment (paypal) transactions
[FIX] im_char: correct display over kanban view
[FIX] gamification: prevent traceback in goals history

Closes #1536
[FIX] website: use internal route for SEO suggest keyword, old server is down
[FIX] res_partner: commercial partner sync

On child partner creation of a parent partner, the commercial_partner_id is not computed (and stored) in the create method.
Therefore, we should compute the commercial_partner_id before trying to sync his data
[FIX] website: encode param for seo search, else multi words will not work.
[FIX] procurement: missing variable

scheduler_cron_id was not initialised so the scheduler always crashed (with just info message)
[FIX] mrp: duplicated find bom buttons

The product_id field is not required on a mrp.bom (while product_tmpl_id is). When searching for BOMs linked to a product.product, we should display the one specific to this product and the ones linked to the template (but not linked to another variant).