运行环境：LNMP
版本：fecmall 2.1.6
安装配置好后，后台访问一切正常；前台部分正常，部分不正常，即 有些菜单及产品可以正常访问与显示，有些却会出现如下报错：
Imagine\Exception\RuntimeException
imagejpeg(/home/leyuxuan/www/fecshop/appimage/common/media/catalog/product/cache/bd935443df1c50537d4edaab4af5d446/50/55/2/01/20161024170457_10036.jpg): failed to open stream: Permission denied
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Caused by: ErrorException
imagejpeg(/home/leyuxuan/www/fecshop/appimage/common/media/catalog/product/cache/bd935443df1c50537d4edaab4af5d446/50/55/2/01/20161024170457_10036.jpg): failed to open stream: Permission denied
in /home/leyuxuan/www/fecshop/vendor/imagine/imagine/lib/Imagine/Gd/Image.php at line 580
