Display updated memo on save

Updating a memo isn't displayed to the user on save. User has to perform some action such as re-edit or go back, to see the changes. Added $scope.$apply() to make sure changes are displayed to the user.

src/js/controllers/tx-details.js

@@ -119,6 +119,7 @@ angular.module('copayApp.controllers').controller('txDetailsController', functio
           $log.debug('Could not save tx comment ' + err);
         }
       });
+      $scope.$apply();
     });
   };