Fix #281

(From the readme:)
> Typically, your controller code will look like this:
`@users = User.order(:name).page params[:page]`

When someone uses `?page[]=` in the url, rails will convert `params[:page]` to an Array, which does not have `to_i`.

This PR will try to use `to_i` (if possible) or default to 0.

For more info + previous discussion refer to #281.