[FIX] don't coerce values to str before writing them to the worksheet in excel export
[FIX] don't coerce values to str before writing them to the worksheet in excel export

especially since xlwt is perfectly able to deal with unicode instances without blowing up like a 'tard

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