Profiling in end to end tests

[Dorran Howell]

Now that we have an end to end test for liquidation auctions, it would be interesting to add some basic execution time (edit: gas cost) profiling to the various liquidation auction methods to attempt to detect degenerating efficiency (e.g. non-constant complexity for cancelling slices). As a part of this we can also shuffle the order of slices to ensure we are touching slices interior to the queue as suggested here #193 (comment).

[Arthur Breitman]

By time, we should mean gas consumption really.