Pillowfight: Properly handle timings

- Don't spam the screen with timings for each iteration. Print them rate
  limited for each second.
- Fix header printing

Change-Id: I80465a4c067e4991e9e2d3936aade2c6cc1f4e8b
Reviewed-on: http://review.couchbase.org/38592
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Brett Lawson <brett19@gmail.com>