Also made some cosmetic cleanups.
Author: Aaron Staple <aaron.staple@gmail.com>
Closes#2385 from staple/SPARK-1087 and squashes the following commits:
7b3bb13 [Aaron Staple] Address review comments, cosmetic cleanups.
10ba6e1 [Aaron Staple] [SPARK-1087] Move python traceback utilities into new traceback_utils.py file.