PARQUET-108: Parquet Memory Management in Java

PARQUET-108: Parquet Memory Management in Java.
When Parquet tries to write very large "row groups", it may causes tasks to run out of memory during dynamic partitions when a reducer may have many Parquet files open at a given time.

This patch implements a memory manager to control the total memory size used by writers and balance their memory usage, which ensures that we don't run out of memory due to writing too many row groups within a single JVM.
Hey, making the same change in this version of DataWritableWriteSupport is ok. What I am trying to say is that the definitive name for this config should be  ParquetOutputFormat not HiveConf. This will allow both versions of DataWritableWriteSupport to use the property.

Does this make sense?