Add tests to show how defining these constants doesn't work on 5.19.x
v0.07

    - No code changes at all. Just added tests to show that defining
      constant subs like I'm doing it doesn't work under 5.19.x (see
      "Re: How about having a recommended way to add constant subs
      dynamically?" on perl5-porters) --
      http://code.activestate.com/lists/perl5-porters/206929/

      I'll fix that in future releases, but first I want to get some
      test coverage on how defining constants works (or doesn't work)
      on different perl versions.