Add speed index unit test

This is a some sample data and assertions I was using while testing the telemetry speed index. This test should only pass if all of the paint events except for the first one are counted, and the largest paint event is discounted by 50%.

When I first ran this test I had some mysterious problems -- runAllTests.php wouldn't detect this test until I renamed tests/testWorkDone.php, and then tests/testPcapUpload.php was throwing errors. (Then, when Pcap errors was moved away, this test was run and it suceeded.)