Updated Travis CI.

Author: tdulcet

.travis.yml

@@ -8,15 +8,25 @@ env:
     - PUBLIC_IPV6=auto
     - PRIMARY_HOSTNAME=auto
     - SKIP_NETWORK_CHECKS=1
+matrix:
+  include:
+  - name: "Install on Ubuntu 14.04"
+    dist: trusty
+    install:
+    - git checkout -q v0.30
+    # Fixes a issue with Travis CI and SpamAssassin. See here: https://github.com/travis-ci/travis-ci/issues/8906#issuecomment-351884500
+    - sudo rm -f /opt/jdk_switcher/jdk_switcher.sh
+  - name: "Install on Ubuntu 18.04"
+    dist: bionic
+git:
+  depth: false
 
 before_script:
     # Adds a hostname to the hosts file.
     - sudo sed -i "s/^127.0.1.1.*/127.0.1.1\t$HOSTNAME.example.com\t$HOSTNAME/" /etc/hosts
     # Updates the apt package database and upgrades all currently installed packages.
     - sudo apt-get -yqq update
-    - sudo apt-get -yqq dist-upgrade
-    # Fixes a issue with Travis CI and SpamAssassin. See here: https://github.com/travis-ci/travis-ci/issues/8906#issuecomment-351884500
-    - sudo rm -f /opt/jdk_switcher/jdk_switcher.sh
+    - sudo apt-get -yqq --allow-unauthenticated dist-upgrade
 
 script:
     # Runs the script.