Enhancement: Add scope_options inspection method to named_scope

When generating complex options hashes for named scopes, it can be difficult to test that the scopes are generated correctly. By providing insight into the generated options, we can test the scope without having to instantiate records.

class Shirt < ActiveRecord::Base
  named_scope :colored, lambda { |color|
    { :conditions => { :color => color } }
  }
end

class ShirtTest < Test::Unit
  def test_colored_scope
    red_scope = { :conditions => { :colored => 'red' } }
    blue_scope = { :conditions => { :colored => 'blue' } }
    assert_equal red_scope, Shirt.colored('red').scope_options
    assert_equal blue_scope, Shirt.colored('blue').scope_options
  end
end