[api] Remove ConditionalGet caching from taxonomies controller

This was being tempremental in my testing
[api] convert incoming payment attributes to an array if they're passed as a Hash

This can happen when using things like Backbone.Syphon and passing in data
[api] include display_total in Orders results
[api] include display_amount in adjustment responses
[api] return method_type in payment method responses
[api] include options_text in variants response
Rename payment method factory that's using BogusSimple gateway from 'authorize_net_payment_method' to 'bogus_simple_payment_method' to reduce confusion in what the factory actually does
'Correctly' define zones association on 'create_shipping_method_zone' migration

Fixes #3307

The issue happened upgrading a 1.3 app to 2.0. What would happen is that this migration expected the table to be called shipping_methods_zones, but a later migration (and a model change in the shipment model) changes this to being spree_shipping_method_zones. This small model code here will redefine the association and appease the migration running script.