Provide a mixin to override AR::Base#to_json

Fixes #192.

lib/active_record/serializer_override.rb

@@ -0,0 +1,16 @@
+# We do not recommend that you use AM::S in this way, but if you must, here
+# is a mixin that overrides ActiveRecord::Base#to_json and #as_json.
+
+module ActiveRecord
+  module SerializerOverride
+    def to_json options = {}
+      active_model_serializer.new(self).to_json options
+    end
+
+    def as_json options={}
+      active_model_serializer.new(self).as_json options
+    end
+  end
+
+  Base.send(:include, SerializerOverride)
+end