PARQUET-132: Add type parameter to AvroParquetInputFormat.

Author: Ryan Blue <blue@apache.org>

Closes #84 from rdblue/PARQUET-132-parameterize-avro-inputformat and squashes the following commits:

63114b0 [Ryan Blue] PARQUET-132: Add type parameter to AvroParquetInputFormat.
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