Repsect autosave: false on nested attributes.

[ fix #2959 ]

Conflicts:
	spec/mongoid/nested_attributes_spec.rb
Fix counter cache to use relation name when possible.

[ fix #2970 ]

Conflicts:
	spec/mongoid/relations/counter_cache_spec.rb
	spec/mongoid/relations/metadata_spec.rb
Timeless scopes properly to class and not thread.

[ fix #2992 ]

Conflicts:
	spec/mongoid/threaded_spec.rb
Fix changelog
fix counter_cache_spec merge errors
Replicate problem - actually getting a bson_dump error because mongoize is not called on the value
Mongoize the value when building the uniqueness query
Merge branch 'uniqueness-validator-doesnt-mongoize' of https://github.com/KoanHealth/mongoid into 3.1.0-stable