Tell Travis to use Firefox 23 (last supported by our older version of Selenium WebDriver)
Use a new version of TAL Test Runner 0.0.2

- Returns a non-zero exit code if Selenium WebDriver fails to start
- Does not use a newer version of WebDriver (this required Ruby >= 1.9.2,
  which our non-Travis CI environments do not have out of the box)
Merge pull request #178 from fmtvp/ttr-travis

TAL Test Runner 0.0.2, and tell Travis CI to use Firefox 23