Version update

Merge pull request #567 from Shopify/express-button-fix

Fix JS syntax on StorefrontExpressButtons

Merge pull request #481 from humancopy/master

Add events to notify of drawer opening / closing

Merge pull request #517 from Shopify/cart-drawer

Disable cart drawer when setting is page

Merge pull request #491 from paulmason/master

Issue #468 - Twitter card descriptions

Merge pull request #472 from Shopify/amazon_payments

Add amazon payments icon

Merge pull request #466 from Shopify/data-sku

Add data-sku to option on product page

Merge pull request #425 from Shopify/mixin-update

Mixin fixes (typo, defaults)

Merge pull request #403 from Shopify/ajax-cart-submit

Let ajax cart submit as normal form with proper quantity

Merge pull request #364 from Shopify/homepage

Home page to homepage