Lock to Rack 1.x and ActiveSupport 4.x
Lock to Rack 1.x and ActiveSupport 4.x

This library isn't (necessarily) incompatible with Rails 5, however we test on
older Rubies, and it's broken on those.

This appears to be due to a Bundler bug:

https://github.com/bundler/bundler/pull/4650

square/rails-auth,square/rails-auth