use factory to generte intergers in space

start with just integer factory in space
change all the hand-out code
still #14

test/parfait/test_integer.rb

@@ -31,18 +31,6 @@ module Parfait
       assert_equal 20 , @int.set_internal_word( Integer.integer_index , 20 )
       assert_equal 20 , @int.get_internal_word( Integer.integer_index )
     end
-    def test_integer_first
-      assert Parfait.object_space.next_integer
-    end
-    def test_integer_20
-      int = Parfait.object_space.next_integer
-      20.times do
-        assert int
-        assert_equal Parfait::Integer , int.class
-        assert int.get_internal_word(1)
-        int = int.next_integer
-      end
-    end
     def test_set
       @int.set_value(1)
       assert_equal 1 , @int.value