After pulling from Github and adding the project, make sure to add the JSON library. It is located in the /lib subfolder. To do this:
- Right click on the project and click Properties, or highlight the project and go to File -> Properties
- Go to Java Build Path and select the "Libraries" tab
- Click the Add Jars button
- Find the JSON library inside the /lib folder, and add it
- All JSON will work from this point