Small improvements your extension

Hello!
This PR adds the following:
* Modman support
* Rewrites Mage_Page_Block_Html_Head
   - allows for getCssJsHtml('js') and getCssJsHtml('css')
   - this way all JS goes in the footer and all CSS can stay in the <head>
   - debug ability included for laterscripts-js.log and laterscripts-css.log
* Edits to footer_scripts.phtml for using getCssJsHtml('js')
* Edits to head_script_less.phtml for using getCssJsHtml('css')
* Edits to Megentoo_LaterScripts_Helper_Data to allow for dynamically disabling the module on the "checkout/onepage". I found some issues with your extension and this page. I think it would be neat addition to allow for configuring pages that disable the extension in the System->Config. Maybe a comma separated list?

> NOTE: if you already have any existing rewrites for "html_head" then this extension may not function as intended until you modify the other rewrites to extend this extensions Megentoo_LaterScripts_Block_Html_Head.