Update to node 10 in .travis.yml

greenkeeper[bot] · greenkeeper[bot] · commit 9891c49e2616 · 2018-04-26T17:00:05.000Z
diff --git a/.travis.yml b/.travis.yml
@@ -4,6 +4,7 @@ node_js:
   - 7
   - 8
   - 9
+  - 10
 script:
   - npm run travis
 after_script:
