Migrating from DVC to Zarr

DVC has been quite bloated, we don't need its most ML pipeline features, and many storage-related features are missing. This upgrade would break all the APIs but it should be good in the long run.

Note: DVCStore at S3 remote has been deleted, so old APIs are not working anymore.

fix IO error in notebook

v0.1.1

update version in setup.py

v0.1.0

update README