$ brew update
$ brew install rbenv ruby-build
$ echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bash_profile
$ echo 'eval "$(rbenv init -)"' >> ~/.bash_profile
$ rbenv versions
$ rbenv install 2.2.2
$ rbenv global 2.2.2
$ cd path/to/repo
$ rbenv local 2.2.2