composer create-project laravel/laravel=5.0.* --prefer-dist
composer create-project laravel/laravel=5.0.* demo --prefer-dist
composer create-project laravel/laravel your-project-name --prefer-dist "5.1.*"
installer 不支持安装其它版本,这是 源码,可以看到代码里面并没有其他选项。