composer http://packagist.org co

重新设置composer packagist，命令如下：
1.（1） composer config -g repo.packagist composer https://packagist.phpcomposer.com
（2）阿里云镜像：composer config -g repo.packagist composer https://mirrors.aliyun.com/composer/

2.重新加载插件 php composer.phar require --prefer-dist 插件名称