adds bundle names so it's bundle_name.zip instead of download.zip
Merge pull request #653 from codalab/feature/zip-file-names-fixed

adds bundle names (bundle_name.zip instead of download.zip)
browse bundle file content.

issue #610
Merge branch 'refs/heads/feature/worksheet_interface' into feature/561-edit-bundle-metadata
#561 don't bother tracking the data type of metadata values, let the backend handle that