Impacted versions:10

Steps to reproduce:
Following the code in https://www.odoo.com/documentation/10.0/api_integration.html both in a fresh install and against 'https://demo.odoo.com/start' trows a type error

Current behavior:
Now I get an error when executing:

```
ids = models.execute_kw(db, uid, password,  'res.partner', 'search',
    [[['is_company', '=', True], ['customer', '=', True]]],
    {'limit': 1})
[record] = models.execute_kw(db, uid, password,
    'res.partner', 'read', [ids])
# count the number of fields fetched by default
len(record)
```

In particular it seems to be a type error (cannot marshal class odoo.tools.float_utils.float_precision)

Expected behavior:
I would expect it to behave as in the documentation

type = 'date'
    @staticmethod
    def today(*args):
        """ Return the current day in the format expected by the ORM.
            This function may be used to compute default values.
        """
        return date.today().strftime(DATE_FORMAT)
    @staticmethod
    def context_today(record, timestamp=None):
        """ Return the current date as seen in the client's timezone in a format
            fit for date fields. This method may be used to compute default
            values.
            :param datetime timestamp: optional datetime value to use instead of
                the current date and time (must be a datetime, regular dates
                can't be converted between timezones.)
            :rtype: str
        """
        today = timestamp or datetime.now()
        context_today = None
        tz_name = record._context.get('tz') or record.env.user.tz
        if tz_name:
            try:
                today_utc = pytz.timezone('UTC').localize(today, is_dst=False)  
                context_today = today_utc.astimezone(pytz.timezone(tz_name))
            except Exception:
                _logger.debug("failed to compute context/client-specific today date, using UTC value for `today`",
                              exc_info=True)
        return (context_today or today).strftime(DATE_FORMAT)
    @staticmethod
    def from_string(value):