Implement Scope#class, Scope#inspect, LayoutScope#class and LayoutScope#

Not sure if this is the desired implementation of these methods, but it should be a starting point for enhancment and discussion.

cc @joneslee85, @jodosha 
I'd use this [trick](http://stackoverflow.com/questions/9197586/how-do-i-get-the-class-of-a-basicobject-instance):

```ruby
class Foo < BasicObject
  def class
    (class << self; self end).superclass
  end
end

Foo.new.class # => Foo
Foo.new.class == Foo # => true
```