Run ESLint turing script phase so build fails

Failures in after_success don’t actually fail the build.

.travis.yml

@@ -46,11 +46,13 @@ before_install:
 
 script:
   - npm install
+  - if [ $TRAVIS_OS_NAME == "linux" ] && [ $TRAVIS_NODE_VERSION == "4" ]; then
+      npm run lint || exit 1;
+    fi
   - npm test
 
 after_success:
   - if [ $TRAVIS_OS_NAME == "linux" ] && [ $TRAVIS_NODE_VERSION == "4" ]; then
-      npm run lint;
       npm run-script coverage;
     fi