recursively_embeds_many breaks with accepts_nested_attributes_for

[malan]

This fix [https://github.com//issues/1244 ] solved the recursively_embeds_many problem however if you have:

class Category
include Mongoid::Document
recursively_embeds_many
accepts_nested_attributes_for :child_categories

(addition of accepts_nested_attributes_for) then it still causes an infinite loop