Add interface layer between Parquet and Hadoop Configuration

Parquet relies heavily on a few Hadoop classes, such as its Configuration class, which is used throughout Parquet's reading and writing logic. If we include our own interface for this, this could potentially allow users to use Parquet's readers and writers without the Hadoop dependency later on.

In order to preserve backward compatibility and avoid breaking downstream projects, the constructors and methods using Hadoop's constructor should be preserved for the time being, though I would favour deprecation in the near future.

This is part of an effort that has been discussed on the dev mailing list.