Ensure something is written on the output each minute.
It helps maven builds when executed with -q or a customized log level
and a lot of things is happening behind the scene (avoids "false" Travis timeouts).
There are multiple ways to do it but one simple is to grab the jar and pass it in maven ext system properties:
mvn dependency:copy -Dartifact=com.github.rmannibucau:maven-travis-output:1.0.0 -DoutputDirectory=/tmp
export MAVEN_OPTS="-Dmaven.ext.class.path=/tmp/maven-travis-output-1.0.0.jar -B -q -e"