drop support for nodejs 4

Moritz Onken · Moritz Onken · commit 9d381d24493a · 2018-09-06T13:14:00.000-04:00
diff --git a/.travis.yml b/.travis.yml
@@ -2,6 +2,6 @@
   language: node_js
   node_js:
     - stable
+    - 10
     - 8
     - 6
-    - 4
