Seeds a tenant when it's created

Populates spree_roles, spree_countries, spree_states, spree_zones, and
spree_zone_members with the same data that new Spree stores are
poulated with when `rake db:bootstrap` is called.
fixes clone_billing_address mass-assignment of tenant_id
Adds spec examples that perform a full checkout on a tenant
Create seeds without protection
Adds spec to prevent zone issue regression
Sets the default_county_id config value
Merge pull request #19 from jbrien/topic/seeds

Tenants should be created with seed data