Add button to download tgz backups

src/views/app.js

@@ -95,6 +95,10 @@ angular.module('Application').controller('AppController', ['$scope', '$location'
         }
     };
 
+    $scope.getAppBackupDownloadLink = function (backup) {
+        return Client.getAppBackupDownloadLink($scope.app.id, backup.id);
+    };
+
     $scope.onAppClick = function (app, $event) { onAppClick(app, $event, true /* always operator */, $scope); };
 
     $scope.sftpInfo = {