Enable PureScript test-runner (#192)
Enable PureScript test-runner (#192)

- Enable test-runner
- Set average run time for test runner to 3 seconds. The run-time is
  based on running all exercise solutions on a 2015 MacBook Pro. Some
  stats (in seconds):

  - minimum: 2.042
  - maximum: 6.005
  - median: 2.280
  - average: 2.436
icyrockcom/xpurescript,icyrockcom/xpurescript