## What changes were proposed in this pull request?
This pr fixes the behaviour of `format("csv").option("quote", null)` along with one of spark-csv.
Also, it explicitly sets default values for CSV options in python.

## How was this patch tested?
Added tests in CSVSuite.

Author: Takeshi YAMAMURO <linguin.m.s@gmail.com>

Closes #13372 from maropu/SPARK-15585.