Test Parquet interoperability and compatibility with other libraries/systems

As we are implementing Parquet backwards-compatibility rules for Spark 1.5.0 to improve interoperability with other systems (reading non-standard Parquet files they generate, and generating standard Parquet files), it would be good to have a set of standard test Parquet files generated by various systems/tools (parquet-thrift, parquet-avro, parquet-hive, Impala, and old versions of Spark SQL) to ensure compatibility.