use node 4 on ci

yyx990803 · yyx990803 · commit 362138d93e1f · 2015-11-15T20:23:13.000-05:00
diff --git a/circle.yml b/circle.yml
@@ -1,3 +1,7 @@
+machine:
+  node:
+    version: 4
+
 general:
   branches:
     ignore:
