* doc/source/conf.py: html_static_path pointed to nonexisting dir
* Fix indent error in python codes
* Insert blank lines before starting code block
* Enable warning-is-error in setup.cfg to prevent future warnings
* 'all_files' should be 'all-files' in setup.cfg
Change-Id: I7c5bc31be9c95ec78f18f895014a03cb003d7e04