In Chrome 84, mixed content will be completely blocked for security
reasons ([see blog](https://blog.chromium.org/2019/10/no-more-mixed-messages-about-https.html))
Other browsers will probably follow in the next months.

As IoT Boxes don't have a valid certificate before connecting to a DB,
we used mixed passive content to communicate with the boxes.
This won't be possible anymore, and we have no possible way to
communicate directly from the browser to the box.

- When an IoT Box boots without registered DB, a unique code will be
 created with a validity of 5 minutes.
- This code will be shown on the customer display and printed on the
 status ticket.
- The box will call a route on odoo.com and a record will be created
 in odoo.com with the unique code.
- The user will have to enter the code manually in his DB to connect
 to the IoT Box, the DB will then contact odoo.com to search for a
 record containing the unique code. If it's found, the
 `openerp.enterprise.database` will be added to the record.
- The box will then query odoo.com at regular intervals (10 seconds)
 to check if a DB is linked to the code.

Taskid: 2246535
X-original-commit: 05de66e6ea815e32b463f1e49e974d30fcf05ac4