lotus/validations — pull request #15 by rail44 (2014-09-18 11:39:50+00:00)
Title: Support nested validation

Hi.

In recent, Custom `type` validation is added.
However, it is diffcult to tell that given param is unvalid for custom type.
If this PR is merge, we can write that like
```
class User
include Lotus::Validations
attribute :name, presence: true
attribute :age
end

class FriendShip
include Lotus::Validations
attribute :user, type: User
attribute :friend, type: User
end
```

Thank you.