added Guest Checkout, check for signature at notification and redirect, send signature, timestamp, and order id instead of secret in helper, update parameter names
Guest Checkout now always enabled

Letting merchant choose whether or not to enable GC by setting
:credential4 to "true" just didn't seem correct, so I just force GC to
be enabled always
standardize amount param
actually, no need
Add credit to dwolla integration files
remove header comments
centralize the signature verification method
rename credentials params
update tests to reflect the change in credential parameter names
remote comment headers, fix credential var names, fix sig verify fn
Quickpay integration: Fix v6 response parsing

The regexp didn't work with the actual input directly from Quickpay.

Closes #661.
First Data e4: Add store support via TransArmor

TransArmor is an API extension for implementing card number
tokenization.

Closes #563.
MerchantWarrior: Format expiration correctly

According to the MerchantWarrior API documentation, cardExpiryYear and
cardExpiryMonth must meet these conditions:

  cardExpiryMonth
  Example: 05
  Notes: This must be in MM format. The month must be zero-padded if
         it’s less than 10.
  Valid Length: 2 digits.

  cardExpiryYear
  Example: 13
  Notes: This must be in YY format.
  Valid Length: 2 digits.

Closes #665.
Add iconv for ActiveSupport 2.3 under Ruby 2.0
Require Ruby 2.0 compatibility in Travis-CI

Closes #669.
Fix duplicate test methods

A bunch of test methods were duplicated, meaning the first version of
them was not being run. This was revealed by running under Ruby 2.0,
since its test/unit warns about the duplication.
DataCash: Fix remote tests

Closes #670.
Fix GettingStarted.md reference links in README

Closes #671.
Add Transnational gateway

http://www.tnbci.com/

Closes #675.
Authorize.Net: Add Check as a payment method

Closes #676.