How to use it?

I've try to include PaperclipValidations in my Model
example:

```
class Photo < ActiveRecord::Base
  include PaperclipValidations
  has_attached_file :image ....
  validates_dimensions_of :image, :width => 320..3000, :height => 100..3000
end 
```

But when I run "ruby script/server", the error message notice me validates_dimensions_of method not found
