Set shipping address from order in ShipmentSerializer
Add Required, Optional Config
Add additional enable_auto_push config and rename enable_hub to enable_push

Conflicts:
	app/models/spree/order_decorator.rb
	app/models/spree/shipment_decorator.rb
	app/models/spree/stock_item_decorator.rb
	app/models/spree/variant_decorator.rb
	lib/spree/hub/client.rb
Update README
Fix specs

Conflicts:
	spec/models/spree/order_spec.rb
	spec/models/spree/shipment_spec.rb
	spec/models/spree/stock_item_spec.rb
	spec/models/spree/variant_spec.rb
	spec/serializers/spree/hub/order_serializer_spec.rb
	spec/serializers/spree/hub/shipment_serializer_spec.rb
	spec/serializers/spree/hub/stock_item_serializer_spec.rb
	spec/serializers/spree/hub/variant_serializer_spec.rb
OrderSerializer sets json root to 'carts' if order state is not complete

Conflicts:
	spec/serializers/spree/hub/order_serializer_spec.rb
utc updated at, sliding placed_on logic
Closes #23

Conflicts:
	app/serializers/spree/hub/order_serializer.rb
update readme to point to the (wip) spree_hub_handlers extension