blackbox: log the commands that are run Uses ui.log to log which commands are run, their exit code, the time taken, and any unhandled exceptions thrown. Example log lines: 2013/02/09 08:35:19 durham> add foo 2013/02/09 08:35:19 durham> add exited 0 after 0.02 seconds Updates the progress tests because they use a mocked time.time() which these changes affect.