Configure Travis CI to use Chrome addon, install ChromeDriver

.travis.yml

@@ -1,11 +1,18 @@
 language: ruby
 addons:
   postgresql: '9.4'
+  chrome: stable
 rvm:
 - 2.3.2
 cache: bundler
 bundler_args: --without development
 before_script:
+- wget -N https://chromedriver.storage.googleapis.com/2.36/chromedriver_linux64.zip -P ~/
+- unzip ~/chromedriver_linux64.zip -d ~/
+- rm ~/chromedriver_linux64.zip
+- sudo mv -f ~/chromedriver /usr/local/share/
+- sudo chmod +x /usr/local/share/chromedriver
+- sudo ln -s /usr/local/share/chromedriver /usr/local/bin/chromedriver
 - for i in config/*.example; do cp "$i" "${i/.example}"; done
 - bundle exec rake db:setup
 script: