Transformations in Trash are inherited correctly

The problem:
```ruby
class Result < Hashie::Trash
  property :some_property, from: 'someValue'
end

class OtherResult < Result
  # Other properties...
end

Result.transforms # => {'someValue'=>:some_property}
OtherResult.translations # => {}

OtherResult.new('someValue' => 'foo')
# => NoMethodError: The property 'someValue' is not defined for OtherResult.
```