attribute_key_name for ActiveRecord#human_attribute_name can be a symbol

[maca]

Passing a symbol for attribute_key_name will blow because symbol doesn't respond to #humanize.

Changing line 10 to: defaults << attribute_key_name.to_s.humanize

fixes the issue

[dcrec1]

Hi Macario,

thanks for the patch, I'll apply it.

Case you wanna send me a pull request, I can accept it, too :)