Travis builds are failing

[rsoletob]

Error:

Reading package lists...
Building dependency tree...
Reading state information...
Package docker-engine is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
  docker-ce
E: Package 'docker-engine' has no installation candidate
The command "sudo apt-get install -y docker-engine" failed and exited with 100 during .
Your build has been stopped.