limit builds on CI to Node 6

bahmutov · bahmutov · commit dfe6bd5a6261 · 2017-07-10T10:30:12.000-04:00
diff --git a/.travis.yml b/.travis.yml
@@ -3,11 +3,9 @@ cache:
   directories:
     - node_modules
 notifications:
-  email: false
+  email: true
 node_js:
-  - '7'
   - '6'
-  - '4'
 before_script:
   - npm prune
 after_success:
