使用gem安装Github上的东西
1.使用gems.github.com
gem install username-projectname –source http://gems.github.com
2.下载源代码并安装
wget http://github.com/username/projectname/zipball/master
unzip username-projectname-version.zip
cd username-projectname-version.zip
gem build projectname.gemspec
gem install projectname-version.gem