feat(node-8): Adding nodejs 8 support on ci build

.travis.yml

@@ -1,18 +1,28 @@
 sudo: required
 dist: trusty
 language: node_js
-node_js:
-  - "4"
-  - "5"
-  - "6"
-  - "7"
-  - "stable"
+
 env:
-  - NPM_VERSION=4 DISPLAY=:99
-  - NPM_VERSION=3 DISPLAY=:99
+  matrix:
+    - NODE_VERSION="4" NPM_VERSION="3" DISPLAY=:99
+    - NODE_VERSION="5" NPM_VERSION="3" DISPLAY=:99
+    - NODE_VERSION="5" NPM_VERSION="3" DISPLAY=:99
+    - NODE_VERSION="6" NPM_VERSION="3" DISPLAY=:99
+    - NODE_VERSION="6" NPM_VERSION="4" DISPLAY=:99
+    - NODE_VERSION="7" NPM_VERSION="3" DISPLAY=:99
+    - NODE_VERSION="7" NPM_VERSION="4" DISPLAY=:99
+    - NODE_VERSION="8" NPM_VERSION="5" DISPLAY=:99
+    - NODE_VERSION="9" NPM_VERSION="5" DISPLAY=:99
+
+cache:
+  directories:
+    - "node_modules"
+
 before_install:
-  - jdk_switcher use oraclejdk8
+  # Prepare node and npm
+  - nvm install $NODE_VERSION && nvm use $NODE_VERSION
   - npm install -g npm@$NPM_VERSION
+  - jdk_switcher use oraclejdk8
   - "/sbin/start-stop-daemon --start --quiet --pidfile /tmp/custom_xvfb_99.pid --make-pidfile --background --exec /usr/bin/Xvfb -- :99 +extension RANDR -ac -screen 0 1280x1024x16"
 before_script:
   - npm install -g grunt