[SPARK-11322] [PYSPARK] Keep full stack trace in captured exception

JIRA: https://issues.apache.org/jira/browse/SPARK-11322

As reported by JoshRosen in [databricks/spark-redshift/issues/89](https://github.com/databricks/spark-redshift/issues/89#issuecomment-149828308), the exception-masking behavior sometimes makes debugging harder. To deal with this issue, we should keep full stack trace in the captured exception.

Author: Liang-Chi Hsieh <viirya@appier.com>

Closes #9283 from viirya/py-exception-stacktrace.