Add date validation

[franckverrot]

validates :birth_date, :date => :past
validates :died_on, :date => :future

something like that :)

[oriolgual]

Maybe you could use an existing solution (ours :P) https://github.com/codegram/date_validator

If you need any help integrating it I'll be glad to help!

[franckverrot]

I've copied your test file to make sure your validator was available thru this gem. Thanks!