ci(travis): update node v4.3.0...4.8.0

Author: michael-ciniawsky

.travis.yml

@@ -7,27 +7,27 @@ matrix:
   fast_finish: true
   include:
     # - os: linux
-    #   node_js: '7'
+    #   node_js: '8'
     #   env: WEBPACK_VERSION="2.2.0" BITHOUND_CHECK=true JOB_PART=lint
     - os: linux
-      node_js: '7'
+      node_js: '8'
       env: WEBPACK_VERSION="2.2.0" JOB_PART=test
     - os: linux
-      node_js: '4.3'
+      node_js: '4.8'
       env: WEBPACK_VERSION="2.2.0" JOB_PART=test
     - os: linux
       node_js: '6'
       env: WEBPACK_VERSION="2.2.0" JOB_PART=test
     # - os: linux
-    #   node_js: '7'
+    #   node_js: '8'
     #   env: WEBPACK_VERSION="2.2.0" JOB_PART=coverage
 before_install:
   - nvm --version
   - node --version
 before_script:
-  - if [ "$WEBPACK_VERSION" ]; then yarn add webpack@^$WEBPACK_VERSION; fi
+  - if [ "$WEBPACK_VERSION" ]; then npm i webpack@^$WEBPACK_VERSION; fi
   # - if [ "$BITHOUND_CHECK" ]; then npm install -g bithound; bithound check git@github.com:$TRAVIS_REPO_SLUG.git; fi
 script:
-  - yarn run travis:$JOB_PART
+  - npm run travis:$JOB_PART
 after_success:
   - bash <(curl -s https://codecov.io/bash)