Restructure module code. Remove logic from template file via a Block cla...

Hi,

a fairly large restructure of your modules code ;)

1. Introduce a block class to deal with the logic of the .phtml display. This removes the logic etc out of the template / display layer
2.  Change location of the template file to templates/glixgalore/checkout/success.phtml (thus containing modules code into its own template folder, and not mixing with theme checkout files)
3. Change the layout.xml to use before_body_end (rather than content) - this ensures code always appears after content in generated html.
4. Change location of all files in repo to be as per module location in magento. Updated modman accordingly. This allows for easy install by non modman users to allow simply copy of files to magento root.
5. Introduce composer.json installer file.