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

"""Returns the given timestamp converted to the client's timezone.
           This method is *not* meant for use as a _defaults initializer,
           because datetime fields are automatically converted upon
           display on client side. For _defaults you :meth:`fields.datetime.now`
           should be used instead.
           :param datetime timestamp: naive datetime value (expressed in UTC)
                                      to be converted to the client timezone
           :rtype: datetime
           :return: timestamp converted to timezone-aware datetime in context
                    timezone
        """
        assert isinstance(timestamp, datetime), 'Datetime instance expected'
        tz_name = record._context.get('tz') or record.env.user.tz
        utc_timestamp = pytz.utc.localize(timestamp, is_dst=False)  
        if tz_name:
            try:
                context_tz = pytz.timezone(tz_name)
                return utc_timestamp.astimezone(context_tz)
            except Exception:
                _logger.debug("failed to compute context/client-specific timestamp, "
                              "using the UTC value",
                              exc_info=True)
        return utc_timestamp
    @staticmethod
    def from_string(value):