Logging change suggestion

[Jim <ji...@gmail.com>]

Hello,

I just had a commit to Spark accepted that fixes the management of 
Parquet logging:

https://github.com/apache/spark/pull/3271

The Spark project committer (Michael Armbrust) suggested I mention the 
issue to you guys. If you notice the code in Spark you need to bend over 
backward to control/integrate Parquet logging into any other project 
that uses Parquet. This is primarily for 2 reasons:

1) Direct use of java.util.logging
2) The static initializer in parquet.Log

I would like to suggest that slf4j be used. This will decouple the 
choice of specific logger and allow the users of Parquet to specify it. 
It will also make the use of the static initializer unnecessary.

Just a suggestion.
Jim