allow boolean last argument in memoized methods - Closes #1704

If in the memoized method, the last argument is a boolean, it's considered as the reload method.
Don't consider it like that if that's a normal method argument.

activesupport/lib/active_support/memoizable.rb

@@ -79,7 +79,11 @@ def #{symbol}(reload = false)                                          #   def m
           else                                                                     # else
             def #{symbol}(*args)                                                   #   def mime_type(*args)
               #{memoized_ivar} ||= {} unless frozen?                               #     @_memoized_mime_type ||= {} unless frozen?
-              reload = args.pop if args.last == true || args.last == :reload       #     reload = args.pop if args.last == true || args.last == :reload
+              args_length = method(:#{original_method}).arity                      #     args_length = method(:_unmemoized_mime_type).arity
+              if args.length == args_length + 1 &&                                 #     if args.length == args_length + 1 &&
+                (args.last == true || args.last == :reload)                        #       (args.last == true || args.last == :reload)
+                reload = args.pop                                                  #       reload = args.pop
+              end                                                                  #     end
                                                                                    #
               if defined?(#{memoized_ivar}) && #{memoized_ivar}                    #     if defined?(@_memoized_mime_type) && @_memoized_mime_type
                 if !reload && #{memoized_ivar}.has_key?(args)                      #       if !reload && @_memoized_mime_type.has_key?(args)