Shopify/identity_cache — pull request #99 by arthurnn (2013-11-28 21:16:08+00:00)
Title: Add require to AS attribute_accessors

### Problem
ActiveSupport 4+ doesnt require attribute_accessors by default, so we need to include it. So `mattr_accessor` wont work.

### Solution
We just need to require it.

This is a pretty small change, it wont hurt backwards compatibility with rails 3.

review @dylanahsmith or @jduff