Travis has updated its docker images, and as part of the update,
no longer includes support for the (deprecated) docker-engine
package, moving instead to docker-ce.
This updates the travis configuration to pin the docker library
version to 17.05.0 and installs the corresponding version of
docker-ce in the install script.
Travis has updated its docker images, and as part of the update, no longer includes support for the (deprecated) docker-engine package, moving instead to docker-ce.
See https://blog.travis-ci.com/2017-06-21-trusty-updates-2017-Q2-launch for details of the package change.
This updates the travis configuration to pin the docker library version to 17.05.0 and installs the corresponding version of docker-ce in the install script.