Add changelog entries for default address and credit card

See #5108 and #5148 for the actual changes.
Added payment source import from Order hash.

Fixes #5145
Fixes #5147
Fix source import specs.
Payments pass source not source_attributes.
Add default ReturnAuthorizationReasons

As per chat w/ @JDutil on IRC

Also fix similar ReimbursementType migration

Fixes #5154
RMA form fix and cancel fix

- Remove form field when the return item cannot be added.  Looks weird and it also causes nested attributes to raise.
- Cancel associated return items when canceling an RMA.  Return Item validations will ensure they can be canceled.

Fixes #5156
Stop spree_sample:load creating a duplicate record

Spree::ShippingCategory.create!(:name => "Default") is run in the following migration https://github.com/spree/spree/blob/master/core/db/migrate/20130830001033_add_shipping_category_to_shipping_methods_and_products.rb therefore a create command here would create a duplicate if a db:migrate had been run prior. shipping_categories.rb could be removed from samples completely but users of db:reset (that uses db:schema:load and loads the db from schema not migrations) would need it to be created here.

Fixes #5161
Revert ReimbursementItem model

This removes ReimbursementItem model and squishes it back into the ReturnItem model.
We split this model out of ReturnItem and we still think that's a good idea.  But we've run into some issues with it so we'll have to look at adding it back in later when we can work through all the details.

Fixes #5160
Make return item eligibility validator more extensible. Add a validator for RMA presence
Fixes #5159
Fix load_user_roles. Fixes #5141
Mark inventory units as shipped in order importer.
Allow posting to ResourceController without parameters

When the associated model doesn't require any attributes.
Needed this for some returns & exchanges stuff.
Similar to 3be886f7de8a2f8515633c4d1d218140dc4373bc

Also, beef up ResourceController specs a bit.