Add a new test
Minor: tweak to just-added test
Switch Tickets back to being pointers.  GHC >=7.6 solution only.
Squashed commit of the following:

commit 15fc0453c1cf0751ae14fd6a7791249877a05edb
Author: Ryan Newton <rrnewton@gmail.com>
Date:   Sat Apr 27 16:50:09 2013 -0400

    Port Michael Scott over to the slightly different CAS interface

commit 355025c81ea1bf1d9f2748a151b94b88120f7c47
Author: Ryan Newton <rrnewton@gmail.com>
Date:   Sat Apr 27 16:35:29 2013 -0400

    Fix the bug.  Same bug as before!  Passes all tests now with NO failures due to GC.

commit 9dd03759e1658d37f0d6c5d0ffb5e79cb2f96b46
Author: Ryan Newton <rrnewton@gmail.com>
Date:   Sat Apr 27 15:31:29 2013 -0400

    [AtomicPrimops] First try to move tickets back to being pointers.  all_hammer_one test fails half the time.