1. A method for modifying a configuration file, the method comprising operating a computing device to perform steps of: receiving at a second computer a first configuration file from a first computer to configure an application to be executed on the second computer; receiving user input at the second computer and modifying the first configuration file to generate a second configuration file on the second computer to configure the application; determining that a third configuration file from the first computer has been received at the second computer, the third configuration file being a revised version of the first configuration file; retrieving the first configuration file; determining a first difference between the first configuration file and the third configuration file, representing differences in configuration files from the first computer; determining a second difference between the first configuration file and the second configuration file, representing differences in configuration files made by a user at the second computer; and receiving user input at the second computer and generating a fourth configuration file to configure the application based on the first difference and the second difference.