Linus Jahn authored May 09, 2018 and Jonah Brüchert committed May 09, 2018

Due to a change at travis-ci, apt update won't be executed at container start
up. Possibilities are to enable it in the travis.yml explicitly again or to do
it manually. Doing it manually is better for us, because we don't need another
apt update at start up for ubuntu touch builds.