Added more totals to cart/cart template
Added ShippingRate js model
Added shippingRates() to Cart service
Updated cart sync to use `use_billing` attr
Updated cart service to cast totals to numerics
Updated shipping-rates-selection directive to use live service
Updated shipping-rates-selection directive template to show when refreshing/no rate available
Added updateTotals() to Order model
Added logic to sync shippment_method_id