[ADD] Kanban: Added kanban_image function in rendering context.
[ADD] Kanban: Added kanban_image function in rendering context.

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