add remote track tests
abstract payment tokens
add unit tests for apple pay xml injection
add placeholder remote tests for auth.net apple pay transactions, fix whitespace
Update failing PayPal remote refund test

In August 2010 PayPal updated how refunding Purchases work, so that they retained the Fixed Fee portion of the Purchase Payment Fee (the $0.30 in 2.9% + 0.30).
Fix typo
Merge pull request #1438 from Shopify/fix-paypal-remote-test-for-transaction-fee-refunds

Update failing PayPal remote refund test
Merge pull request #1439 from Shopify/typo-fix

Fix typo
Add error_code to ActiveMerchant::Billing::Response and use it with strip error codes
added mercury certification test cases
Revert "added mercury certification test cases"

oops
This reverts commit d3475044a8b2f59f4bed279a8cfb42da11f7ba12.
added credit_card_track_data method
Merge pull request #1435 from Shopify/error_codes

Standardizing error codes
Conekta: Add a remote test

There is some functionality in the Conekta gateway allowing one to
specify things like line items and customer name using the options hash.
We now have a remote test actually hitting it.
TNS: Update countries and supported card types

Closes #1440.
Conekta: Add AMEX as a supported card type

Closes #1424.
auth_net should take care of encoding apple pay token as needed
replace Authorize.Net credentials with Apple Pay-enabled ones
move apple_pay_payment_token into Auth.Net remote tests, since all data is specific to Auth.Net, simplify apple pay token tests
review items: mention freshness of test credentials, realistic instantiation of ApplePayToken objects in test, style polish