Shopify/active_merchant — pull request #245 by lest (2012-01-03 09:12:02+00:00)
Title: handle Base64 properly

ActiveSupport::Base64 was deprecated in Rails 3.2 and removed in 4.0

3-2-stable
https://github.com/rails/rails/commit/5f09414f85edfa60ab54ce8b9f8b03874e0670dc#diff-5

master
https://github.com/rails/rails/commit/0f2f8003d2351079ce6ec0e706e474d8024839cc#diff-6