Fix setup readlink resolution

[montoyaedu]

Hello,

Just a note so i wont forget it.

I was playing with quickfast and liquibook on my osx box and i found a problem with readlink on BSD systems.

I added some code to setup.sh in order to resolve the correct readlink program.

On an osx box, we should install coreutils that provided greadlink.

It can be done through homebrew by issuing

brew install coreutils

Please verify if this solution can provide a more robust implementation of the setup shell script.

Thanks,

Edu.