Getting data from The City's API and persisting it to a database. Maybe something else?
Install Ruby. If you're on Windows, get this from http://rubyinstaller.org/downloads/ . This was developed targeting 2.1.5.
If you're on Windows, install the Ruby DevKit. This can be retrieved from the previous link.
Install the JSON gem. Do this by running gem install json in a terminal.
The script should be runnable at this point. If it is not, please open an issue here.