- If a controller is in a namespace, serializer will be looked up in this namespace first.
- Serializers for associations will be looked up in a parent serializer's namespace first too.
- "Prefix" option for different versions of associations serializers. Example: has_many :users, as: :short -> ShortUserSerializer

TODO: tests, config option for enabling namespace lookup
tests for namespaced controlleler
test for namespaced associations + bug fixed
changelog
sync with upstream
fix for ruby 1.9.
typo
Merge pull request #617 from konukhov/namespaced_serializers-0-9

Namespaced serializers #499