Remove active_record require
Remove active_record require

fogisland/grape-active_model_serializers,onomated/grape-active_model_serializers,jrhe/grape-active_model_serializers,Thanx/grape-active_model_serializers,ruby-grape/grape-active_model_serializers,kulte/grape-active_model_serializers,gaugau/grape-active_model_serializers