Build and install libv8 on 10.9 Mavericks, needed to run TheRubyRacer.

instructions

Gist from [here](http://stackoverflow.com/questions/19270108/therubyracer-error-error-while-executing-gem-nomethoderror-undefined-meth)

    git clone https://github.com/cowboyd/libv8.git
    cd libv8
    bundle install
    bundle exec rake checkout
    bundle exec rake compile
    bundle exec rake build
    gem install ./pkg/libv8-3.16.14.3.gem
  
To avoid missing gem on rvm cache:

   cp ./pkg/libv8-3.16.14.3.gem ~/.rvm/gems/ruby-1.9.3-p448/cache

replacing `ruby-1.9.3-p429` with your ruby version.