Added new property in Service data model

Allows the user to enabled external tab integration

app/model/Service.js

@@ -69,5 +69,10 @@ Ext.define('Rambox.model.Service', {
 		 name: 'zoomLevel'
 		,type: 'number'
 		,defaultValue: 0
-	}]
+	},
+	{
+		name: 'allow_external_tab'
+	   ,type: 'boolean'
+	   ,defaultValue: true
+   }]
 });