fix(travis): Wait more specifically for selenium to start

Author: Droogans

.travis.yml

@@ -18,6 +18,6 @@ before_script:
 - sh -e /etc/init.d/xvfb start
 - jdk_switcher use oraclejdk8
 - yarn start > /dev/null 2>&1 &
-- sleep 10
+- while ! curl --silent http://localhost:4444/wd/hub > /dev/null 2>&1; do sleep 1; done
 script:
 - yarn test