Add getters and updaters for street-level store address to API

[allendav]

Knowing the base location city, state, postcode and country is not enough in many US states to calculate sales taxes properly. We also need to know the street address of the business. This is known in the tax business as "rooftop accurate" rates. This issue will be used to add that information to the API

See also woocommerce/woocommerce#15602 and Automattic/wp-calypso#14775