chore(travis): whitelist greenkeeper branches

greenkeeper[bot] · greenkeeper[bot] · commit 1fe685173257 · 2018-08-11T22:11:27.000Z
diff --git a/.travis.yml b/.travis.yml
@@ -6,6 +6,7 @@ node_js:
 branches:
   only:
     - master
+    - /^greenkeeper/.*$/
 
 before_script:
   - npm install
