Author: Holden Karau <holden@pigscanfly.ca>

Closes #6275 from holdenk/SPARK-771-startTime-is-missing-from-pyspark and squashes the following commits:

06662dc [Holden Karau] add mising blank line for style checks
7a87410 [Holden Karau] add back missing newline
7a7876b [Holden Karau] Add a startTime property to match the corresponding one in the Scala SparkContext