[IMP] TransientModel: unnecessary unlink() override
[IMP] TransientModel: unnecessary unlink() override

Workflow instance deletion is taken care of by the
regular Model.unlink() method, by calling 
workflow.trg_delete().
vnc-biz/openerp-server,gisce/openobject-server,splbio/openobject-server,MarkusTeufelberger/openobject-server,splbio/openobject-server,ovnicraft/openerp-server,ovnicraft/openerp-server,gisce/openobject-server,vnc-biz/openerp-server,gisce/openobject-server,splbio/openobject-server,MarkusTeufelberger/openobject-server,MarkusTeufelberger/openobject-server