Removes old implementation of `list_folder`.
Removes old implementation of `list_folder`.

Mavvie/dropbox_api,Jesus/dropbox_api,Jesus/dropbox_api_v2,Mavvie/dropbox_api,Jesus/dropbox_api,Jesus/dropbox_api,luigi-sk/dropbox_api,luigi-sk/dropbox_api,Mavvie/dropbox_api,Jesus/dropbox_api_v2