Fix for issue #2033 - modify the default "delete" batch action to redirect to the collection path via route_collection_path to ensure that the path will work for nested (belongs_to) resources.
* Fixed feature step for submitting batch action form to properly pass the selected rows.
* Corrected the tests in the 'Use default (destroy) batch action' scenario in the batch_actions feature.
Added batch action feature scenario for testing batch action usage with a nested resource.
Merge pull request #2034 from tinynumbers/2033-fix-delete-batch-action-redirect

Fix for #2033 - fix the collection_path for 'delete' batch action