Fix #369: Update download_tools() to account for Dropbox interface change.
Fix #369: Update download_tools() to account for Dropbox interface change.

churchlab/millstone,churchlab/millstone,woodymit/millstone_accidental_source,woodymit/millstone,woodymit/millstone,woodymit/millstone_accidental_source,churchlab/millstone,woodymit/millstone,churchlab/millstone,woodymit/millstone_accidental_source,woodymit/millstone_accidental_source,woodymit/millstone