优化 图片缓存
localstrrage
插件
https://github.com/paveisistemas/ionic-image-lazy-load
https://github.com/sunsus/ngImgCache
https://github.com/sunsus/ngImgCache/blob/master/ngImgCacheIonic.js
ionic webapp
原文：http://www.cnblogs.com/whuper/p/4205972.html
