Notice that `#test_embed_ids_include_true` does actually pass when
side-loading (using `:embed => :ids & :include => true`)
I also included `#test_default_circular_nesting`, which fails
by raising `SystemStackError` when naively using default nesting
on a circular reference. Is this behavior expected?
Makes AMS usable for me with rails 4.2 and current serializer which have
Longer term plan is to load all ember data associations asychronously
and then no need to embed associated models.