[0.6.4] - 2020-09-04

Primarily a range of bugfixes to ensure correct operation with current state
of other components of DANDI, and use of the client on Windows OS.

Added
- Initial DANDI schema files
- More tests for various code paths
- `download`: new option `--download [assets,dandiset.yaml,all]`

Fixed
- `download` - account for changes in DANDI API (relevant only for released
  datasets, of which we do not have any "real" ones yet)
- `upload` - various Windows specific fixes

Note: [0.6.3] was released under missing some of the fixes, so overall
abandoned.