[SPARK-6294] fix hang when call take() in JVM on PythonRDD

The Thread.interrupt() can not terminate the thread in some cases, so we should not wait for the writerThread of PythonRDD.

This PR also ignore some exception during clean up.

cc JoshRosen mengxr

Author: Davies Liu <davies@databricks.com>

Closes #4987 from davies/fix_take and squashes the following commits:

4488f1a [Davies Liu] fix hang when call take() in JVM on PythonRDD