*** UPDATE *** As of Divi 3.0.1 you can now edit the Divi footer credits using the Theme Customizer.
To edit navigate to the Theme Customizer > Footer > Bottom Bar > Edit Footer Credits (scroll down)!
1. Go to your Divi tab > Divi Theme Options > Integration > Add code to the < body > (good for tracking codes such as google analytics)
2. Add the following code;