Add support for Parquet format

[andrewcstewart]

Parquet is likely the preferred format to use in many Athena applications.

Examples

• https://github.com/mirelagrigoras/target-parquet
• https://github.com/transferwise/pipelinewise-target-snowflake

[yummydum]

Adding something like this to formats.py should work

import pyarrow as pa
pa.parquet.write_table(pa.Table.from_pydict(record),filename)