Bring back compat with ActiveModel::Serializers

The current AMS re-write (which will debut as v0.9.0) has changed how
serializers are resovled, and removed the ArraySerializerSupport module.
This change will ensure Draper properly integrates with both AMS
pre-0.9.0, and the future.
Merge branch 'compatibility_with_active_model_serializers_next' into 1.4.x