[FIX] point_of_sale: let the session generate a session_id itself

bzr revid: chs@openerp.com-20140115161651-aht37d2ruf1jyzw6

addons/point_of_sale/static/src/js/devices.js

@@ -119,7 +119,6 @@ function openerp_pos_devices(instance,module){ //module is instance.point_of_sal
         connect : function(url){
             var self = this;
             this.connection = new instance.web.Session(undefined,url);
-            this.connection.session_id = _.uniqueId('posproxy');
             this.status = 'connecting';
 
             return this.message('handshake').then(function(){