small improve

so small improve so working on one branch, big refactor coming next year.

- load Ownership mixin on initializer, refer #281 
- remove `Config.orm_name` method, this only used in test.

ps: some deprecation tip like `DEPRECATION WARNING: `named_routes.helpers` is deprecated, please use `route_defined?(route_name)` to see if a named route was defined. (called from block (3 levels) in <top (required)> at /Users/jasl/workspace/ruby/doorkeeper/spec/controllers/authorizations_controller_spec.rb:63)` seems test gems problem.
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