Embed Node in SimpleSmartAnswerEdition
Workaround mongoid conflicting mods error

See https://github.com/mongoid/mongoid/issues/1219

Overrides update_attributes on SimpleSmartAnswerEdition so that
nested Node documents are updated individually. This circumvents the
problem of mongoid issuing a query with conflicting modifications.
Remove old comment about relations vs embedded
Assert update_attributes behaves as expected
Cleanup whitespace
Merge remote-tracking branch 'origin/embed_smart_answer_node'