Work around broken certificates for OpenJDK 9 on Travis CI (issue tra…

…vis-ci/travis-ci#9368)

.travis.yml

@@ -7,6 +7,8 @@ cache:
   directories:
     - $HOME/.m2
 script:
+  - rm "${JAVA_HOME}/lib/security/cacerts"
+  - ln -s /etc/ssl/certs/java/cacerts "${JAVA_HOME}/lib/security/cacerts"
   - "echo '<settings><servers><server><id>sonatype-nexus-snapshots</id><username>${env.CI_DEPLOY_USERNAME}</username><password>${env.CI_DEPLOY_PASSWORD}</password></server></servers></settings>' > $HOME/settings.xml"
   - "[[ $TRAVIS_PULL_REQUEST == 'false' ]] && export MAVEN_PHASE=deploy || export MAVEN_PHASE=install"
   - "mvn $MAVEN_PHASE -B -U -s $HOME/settings.xml"