:having sanitization

Hi all,

Great to see :having support made it in for 2.3. However I notice
that it isn't sanitizing the conditions, so whereas:
  :having => 'sum(credit_limit) > 50'
works,
  :having => ['sum(credit_limit) > ?', 50]
doesn't. It should do the same as :conditions...

Easy patch: http://rails.lighthouseapp.com/projects/8994-ruby-on-rails/tickets/2158-having-conditions-need-sanitizing

Cheers,
Will

Pushed.

Thanks.