Ckeditor Stripping all attributes, when re-editing content
You shouldn't really hack the config.js file. You can pass any custom configuration values through the admin:


Go to /admin/config/content/ckeditor.
Click on the "Edit" link next to the profile you are working with.
Expand the "Advanced options" fieldset.
Enter the following code in the "Custom JavaScript configuration":

// Instruct CKEditor to disable the filter. You can also limit this to specific tags.
config.allowedContent = true;
// Allow p, div, li and ul tags to have any attributes attached to them.
config.extraAllowedContent = 'p(*)[*]{*};div(*)[*]{*};li(*)[*]{*};ul(*)[*]{*}';



See docs for CKEDITOR.config.allowedContent and CKEDITOR.config.extraAllowedContent. If you are insterested in having this in every Drupal installation, check out my Drupal 7 installation profile.
The file in question is here.

Hope this helps.