ActiveRecord validation with hash key values

AR validation seems to act inconsistently with attribute keys used as assignment, e.g.
user.status = :active # valid
vs
user.status = 1 # invalid
Either should be valid as both are otherwise treated the same way and assignment-by-key converts to value. This allows attributes to be used in hidden_fields since form_helper (properly) uses the [raw value](http://api.rubyonrails.org/classes/ActiveRecord/AttributeMethods/BeforeTypeCast.html#method-i-attributes_before_type_cast) to populate the form value

fix and test included.