CDK-713. Don't use DurableParquetAppender by default.

* This also includes tests to check that ParquetAppender
  is the default, that setting kite.parquet.non-durable-writes
  to false will use the DurableParquetAppender, and that
  setting kite.parquet.non-durable-writes to true will use
  ParquetAppender.

Closes #240