How this module works

The module depends on our little helper module named helloo flex (included). This allows us to inject
html code wherever we want it to be without any overloading of templates in your design
package.

All we need is a layout handle and a block alias. We register them on the block-class named
Helloo_Flex_Model_HtmlExtension on the Helloo_CheckoutComment_Model_Observer
observer to set them before any html block is rendered.

Flex checks the registered blocks after they are rendered and appends/prepends the
registered block-html to the output.

For the helloo checkout comment module this is done for the email templates, the adminhtml order
view and the onepage checkout review.