Add new download button styles from Bug 795976
Bug 820937: Add new download button helper and template.
Bug 820937: Add download_firefox helper and greatly simplified button template.

Bug 795976: Add support for no-js, unrecognized platform, and unsupported platform.
Replace download buttons across the site.
Adjustments to home page for new download buttons
(Bug 795976)
Adjustments to /fx page for new download buttons
(Bug 795976)
IE6 & IE7 fixes for new download buttons
(Bug 795976)
Bug 820622: Add locale to download url path in buttons.
Fix mobile version of /firefox/new/ page logo
Drop custom button styles from /firefox/partners
Bug 795976