updated all parsers to object_path use

Not really sure how I missed this the first time
Now that I'm looking at this again, I'm wondering if we could simplify this.  What do you think about something like this

```ruby
def to_json
  response_options = base_options.merge(item_options)
  MultiJson.dump(response_options)
end

private

def base_options
  { successful: @response.success?, errors: @response.try(:errors) }
end

def item_options
  return {} unless @response.success?
  { 
    transaction: {
      id: ...,
      type: ...,
    }
  }
end
```

Does that strike you as a any more intention revealing?  What's above seems generic enough that you could build a base class and the subclasses for Transaction and CreditCard could just supply their specific ```item_option``` method.