spiders for multiple tasks
从 https://www.graffiti.org 爬取涂鸦 其 .jpg resource的结构遵从以下结构 ____https://www.graffiti.org/index/europe.html |____https://www.graffiti.org/prague/prague_3.html | |____https://www.graffiti.org/prague/scoutscu.jpg | |____https://www.graffiti.org/prague/dskbus.jpg .... |____https://www.graffiti.org/berlin/berlin_6.html |____https://www.graffiti.org/berlin/gpl10.jpg .... ____https://www.graffiti.org/index/usa.html