Parquet Sink v0.2.0

This release improves the developer experience when running locally.

Added

• Add a --persist-to-fs=my-dir flag to persist the indexer's state to the
  filesystem. This option creates a new directory (specified by the user) and
  writes the indexer's current state to a file, with one file per indexer.
  Developers shouldn't use this option for production, but only for
  development since it lacks any locking mechanism to prevent multiple copies
  of the same indexer running at the same time.

Changed

• The transform function now is invoked with a single block of data.