centos7添加阿里云的epel源

有些包在别的yum源找不到，在阿里云的yum源里成功找到，这里记录在不影响base源的情况快速添加epel源的添加方法

wget https://mirrors.aliyun.com/epel/7Server/x86_64/Packages/e/epel-release-7-11.noarch.rpm

rpm -ivh https://mirrors.aliyun.com/epel/7Server/x86_64/Packages/e/epel-release-7-11.noarch.rpm