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

openerp/fields.py
kwargs['string'] = string
        args = {key: val for key, val in kwargs.iteritems() if val is not Default}
        self.args = args or EMPTY_DICT
        self._setup_done = None
    def new(self, **kwargs):
        """ Return a field of the same type as ``self``, with its own parameters. """
        return type(self)(**kwargs)
    def __getattr__(self, name):