[ImgBot] Optimize images

*Total -- 759.49kb -> 484.51kb (36.21%)

/src/common/images/static-jscs.png -- 99.91kb -> 59.56kb (40.38%)
/src/common/images/static-eslint.png -- 107.82kb -> 64.44kb (40.24%)
/src/common/images/static-codesniff.png -- 280.68kb -> 169.36kb (39.66%)
/src/common/images/static-md.png -- 271.08kb -> 191.14kb (29.49%)

Signed-off-by: ImgBotApp <ImgBotHelp@gmail.com>

Author: ImgBotApp