Create ImageCacheManager

图片的内存缓存与本地缓存结合，只是简单的包装，大家试试好不好使，哈哈哈，我是新手，不好使大家一起改。

这个类需要结合 ImageCache和ImageSDCardCache一起使用。
Update ImageCacheManager

修改SDCardCache获取那一步，先去SDCardCache的cache队列查询再去执行onGetData()
更新ImageCacheManager(哈哈，我会用git了！）

用桌面的Git客户端进行修改
添加ImageCacheManager使用方法注释
进一步简化代码
change ImageCacheManager.java
修正例子的小bug
add  whether show footer when no more data in DropDownListView

fix footer also can click when no more data
add CacheManager

you can use CacheManager.getHttpCache to get the singleton instance of HttpCache
modify javadoc
fix drawable be used common leading to imageView scaleType error bug
add tips to add permissions in manifest for ImageCache
Merge pull request #1 from hackoooo/patch-1

Create ImageCacheManager
modify ImageCacheManager
add getImageCache and getImageSDCardCache to CacheManager.java
modify version
add ScreenUtils.java
update http cache info
add getInstallLocation for PackageUtils.java
Merge branch 'master' of github.com:Trinea/AndroidCommon