File download button for ng2 document list

- ability to download the file from the list
- ability to toggle download button via attributes

demo-shell-ng2/app/components/alfresco.service.ts

@@ -28,6 +28,10 @@ export class AlfrescoService {
         return this._host + '/alfresco/service/api/node/' + document.nodeRef.replace('://', '/') + '/content/thumbnails/doclib?c=queue&ph=true&lastModified=1';
     }
 
+    getContentUrl(document: DocumentEntity) {
+        return this._host + '/alfresco/service/' + document.contentUrl;
+    }
+
     private handleError (error: Response) {
         // in a real world app, we may send the error to some remote logging infrastructure
         // instead of just logging it to the console