system ruby ではなく user ruby を使う
$ sudo yum install sqlite-devel sqlite openssl openssl-devel readline-devel readline compat-readline5 libxml2-devel libxslt-devel libcurl curl wget git
$ sudo apt-get install build-essential libreadline-dev libssl-dev zlib1g-dev
$ git clone git://github.com/sstephenson/rbenv.git ~/.rbenv
$ echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bashrc
$ echo 'eval "$(rbenv init -)"' >> ~/.bashrc
$ source ~/.bashrc
$ git clone git://github.com/sstephenson/ruby-build.git
$ cd ruby-build
$ sudo ./install.sh
$ cd ../
# 新しいバージョンを確認
$ rbenv install -l
$ rbenv install 1.9.3-p392
$ rbenv global 1.9.3-p392
$ which ruby
$ which gem
$ gem install foreman sinatra unicorn
# rehashしないとパスが通らないので注意
$ rbenv rehash
$ which foreman
$ which unicorn
$ cd 7kai-Bootstrap
$ foreman start