v0.2.1

"Sedes incertae"

Notable changes:

• Scio now detects BigQuery staging dataset location. #226
  The -Dbigquery.staging_dataset.location flag is removed.
• Bump Bigtable dependency to 0.9.2 which fixed a bug that causes some rows to be read twice #223
• @BigQueryType must now be declared inside a class or object #227
  This is in preparation for further macro improvements.
• Add allowedTimestampSkew to timestampBy #219