Require ActiveSupport's string/inflections

We depend on string/inflections to define String#underscore.

Author: nate00

CHANGELOG.md

@@ -3,6 +3,7 @@
 Breaking changes:
 Features:
 Fixes:
+- [#1488](https://github.com/rails-api/active_model_serializers/pull/1488) Require ActiveSupport's string inflections (@nate00)
 Misc:
 
 ### v0.10.0.rc4 (2016/01/27 11:00 +00:00)

lib/active_model_serializers.rb

@@ -1,6 +1,7 @@
 require 'active_model'
 require 'active_support'
 require 'active_support/core_ext/object/with_options'
+require 'active_support/core_ext/string/inflections'
 module ActiveModelSerializers
   extend ActiveSupport::Autoload
   autoload :Model