安装Rails备忘
相关目录和路径如下：
http://rubyforge.org/frs/?group_id=307 下载rails
http://rubyforge.org/projects/activesupport 下载activesupport
http://rubyforge.org/projects/activerecord/ 下载activerecord
http://rubyforge.org/projects/actionpack 下载actionpack
http://rubyforge.org/projects/actionmailer 下载actionmailer
http://rubyforge.org/projects/aws 下载actionwebservice
http://rubyforge.org/projects/rake 下载rake
http://rubyforge.org/projects/activeresource 下载activeresource