[FIX] aggregate field value can be returned as 'false', which should be translated to '0'
[FIX] aggregate field value can be returned as 'false', which should be translated to '0'

--HG--
extra : convert_revision : xmo%40openerp.com-20110524140648-vvl12y1vyqz5wowi

vnc-biz/openerp-web,splbio/openerp-web,vnc-biz/openerp-web,MarkusTeufelberger/openerp-web,vnc-biz/openerp-web,gisce/openerp-web,MarkusTeufelberger/openerp-web,vnc-biz/openerp-web,splbio/openerp-web,MarkusTeufelberger/openerp-web,splbio/openerp-web,gisce/openerp-web,gisce/openerp-web