Lessons learned from numist/state-machine-parallel-tests
Unfortunately, OCMock isn't thread-safe(!), so more has to change before this can work correctly.
Tests are not likely to run in parallel in the near future.
Revert "An attempt at making the state machine tests run in parallel."

This reverts commit 10b999f.

5e8d633 has more information, but the short story is that OCMock isn't thread-safe.