2.7.4 (2016-11-17)

• Fix coupon redemption errors PR
• Remove "base" from pretty printed error messages PR
• Fix rails deprecation warning PR
• Add updated_at to MeasuredUnit PR
• Support gift card canceled_at timestamp PR
• Fix AddOns quantity accumulator bug from #226 PR
• Fix Ruby 1.9.3 and jruby testing dependencies PR
• Add new dunning event webhook PR
• Add timeframe attribute to Subscription PR