利用nginx在服务器搭建下载功能，
安装Nginx，pcre
mkdir /usr/local/nginx
tar zxvf pcre-8.12.tar.gz
cd pcre-8.12
./configure –prefix=/usr/local/pcre
make && make install
tar zxvf nginx-1.0.12.tar.gz
tar zxvf nginx-1.0.12.tar.gz
cd nginx-1.0.12
./configure –prefix=/usr/
