chore(travis): Add firefox setup

Kent C. Dodds · Kent C. Dodds · commit 3ed9bf5bedbd · 2015-08-28T12:06:29.000-06:00
Our tests run in firefox and we need to inform travis of this using some weird cryptic stuff 😕
diff --git a/.travis.yml b/.travis.yml
@@ -9,6 +9,8 @@ node_js:
   - iojs
 before_install:
   - npm i -g npm@^2.0.0
+  - "export DISPLAY=:99.0"
+  - "sh -e /etc/init.d/xvfb start"
 before_script:
   - npm prune
 script:
