Update TravisCI config

[ruebot]

TravisCI builds are failing now because:

Expected feature release number in range of 9 to 13, but got: 7
The command "~/bin/install-jdk.sh --target "/home/travis/oraclejdk7" --workspace "/home/travis/.cache/install-jdk" --feature "7" --license "BCL"" failed and exited with 3 during .

Java 7 😄