SPARK-3883: Fixes after the review

- Removed license header from ssl.conf.template
- Fixed parameters order in SSLOptions.parse invocation in SecurityManager at L199
- Replaced org.apache.commons.io with different approaches
- Removed unused line of code from SecurityManager
- Changed the default protocol from SSLv3 to TLSv1.2 (POODLE attack)
Merge pull request #1 from jacek-lewandowski/SPARK-3883-fixes-1

SPARK-3883: Fixes after the review