[IMP] simplify code of padding function in date formatting, add some doc, fix name
[IMP] simplify code of padding function in date formatting, add some doc, fix name

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