Determine why the Travis CI tests are failing

They pass locally, just not on Travis CI. It doesn't look like it's code but something in our test setup.

Quicksketch suggests that the problem is that we're using younghttp instead of apache: https://github.com/backdrop/backdrop/blob/1.x/.travis.yml

Furthermore, the problem may also be running out of memory. He suggested tuning settings.php and php.ini. 
