Add format script

[BalaBalaYi]

Add a 'format.sh' to format shell, c++, python, java files.

[ashione]

Thanks for contributing CI/CD format tools. It would be better to add tutorial for other devs or contributors.

[ashione]

I has one suggestion about code lint.
How to execute format.sh and show diff in git diff > diff.txt, and check whether diff.txt is empty.
Non-empty diff content means changes have no lint problems.

Any thoughts about that? @jovany-wang

[jovany-wang]

It seems like what we did in Ray repo https://github.com/ray-project/ray/blob/master/ci/travis/check-git-clang-format-output.sh