Add #scope_with_reputation method to return scoped object instead of Array

Just added #scope_with_reputation in FinderMethods module. 

The effect is similar to #find_with_reputation, with the difference it will return a scoped object instead of Array.

This will help efficiency when dealing with lots of records. 

Also it will be native to work with pagination gems like

    Question.scope_with_reputation(:total_votes, :all).page(1)