Remove js api key that was missed during 2469735fba9720d4cb0895576a197a375d569071
Order#finalize should use save!

save will silently ignore any errors. It is much better to raise an
error than to silently fail.
Merge pull request #4986 from athal7/remove-api-token

Remove js api key that was missed during 2469735fba9720d4cb0895576a197a3...
Order#merge! should use save!
Merge pull request #4989 from jhawthorn/save_bang

Use save! when modifying the order
Add blank to ShippingMethod's TaxCategory select

Addresses https://github.com/spree/spree/issues/4914

Now ShippingMethods whose `tax_category` is `nil` will display a blank selector rather than falsely displaying the first TaxCategory in the system.

Note that due to the UI implementation it appears to be impossible to return to selecting `nil` after a TaxCategory has been selected.
Introduce refund and return authorization reason