An extension for Deploytool that gets a diff of files that have changed between commits
npm install deploytool-git-diff --save
var deploytool = require('deploytool');
deploytool.deploy('production', 'e8ac002dc64111fce77c9c9d12c28c13c3f98aa2');
Take care to follow the same patterns as other Deploytool modules.
Don't extend Deplyotool itself to add new deployment types. Simply create new modules prefixed with deploytool- that has a "deploy" method in it.