PARQUET-114: Sample NanoTime class serializes and deserializes Timestamp incorrectly

I ran the Parquet Column tests and they passed.

FYI @rdblue

Author: Brock Noland <brock@apache.org>

Closes #71 from brockn/master and squashes the following commits:

69ba484 [Brock Noland] PARQUET-114 - Sample NanoTime class serializes and deserializes Timestamp incorrectly