Travis build - replace oraclejdk8 with openjdk8
Travis build - replace oraclejdk8 with openjdk8

Oracle JDK8 is not supported anymore. There are errors like this:

Installing oraclejdk8Installing oraclejdk8
$ export JAVA_HOME=~/oraclejdk8
$ export PATH="$JAVA_HOME/bin:$PATH"
$ ~/bin/install-jdk.sh --target "/home/travis/oraclejdk8" --workspace "/home/travis/.cache/install-jdk" --feature "8" --license "BCL"
Ignoring license option: BCL -- using GPLv2+CE by default
install-jdk.sh 2019-10-16
Expected feature release number in range of 9 to 15, but got: 8
The command "~/bin/install-jdk.sh --target "/home/travis/oraclejdk8" --workspace "/home/travis/.cache/install-jdk" --feature "8" --license "BCL"" failed and exited with 3 during .

play2-maven-plugin/play2-maven-test-projects,play2-maven-plugin/play2-maven-test-projects,play2-maven-plugin/play2-maven-test-projects