Using my previous post on how to turn of the automatic paragraph tags in CKEditor, I knew how to shut this feature off but I didn’t know where.

vim sites/all/libraries/ckeditor/config.js

Then add this to the config section:

CKEDITOR.editorConfig = function( config )
{
        // Define changes to default configuration here. For example:
        // config.language = 'fr';
        // config.uiColor = '#AADC6E';
        CKEDITOR.config.enterMode = CKEDITOR.ENTER_BR;
};

Save and refresh the page.