[FIX] web form : catch and display error when there are an error in an attachment upload
[FIX] web form : catch and display error when there are an error in an attachment upload

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