[FIX] FieldBoolean: `required` attribute should be ignored
[FIX] FieldBoolean: `required` attribute should be ignored

In order to match the model-level bevahior of boolean
fields, the required attribute should be ignored, as
a NULL value is automatically converted to False, and
considered valid. This contrasts with Char fields, but
is similar to Integer/Float fields, for which NULL values
are converted automatically to 0, and considered valid.

havt/openerp-web,havt/openerp-web,akretion/openerp-web,akretion/openerp-web,havt/openerp-web,havt/openerp-web,havt/openerp-web,akretion/openerp-web