ci(travis): Checking npm5 as issue src

Author: joshwiens

.travis.yml

@@ -19,7 +19,7 @@ matrix:
       node_js: '8'
       env: WEBPACK_VERSION="2.6.0" JOB_PART=coverage
 before_install:
-  - 'if [[ `npm -v` != 5* ]]; then npm i -g npm@^5.0.0; fi'
+  - 'if [[ `npm -v` != 4* ]]; then npm i -g npm@^4; fi'
   - nvm --version
   - node --version
   - npm --version