Merge pull request #47 from wei-lee/support-node10

 ⬆ add support for node 10 and drop node 4

Author: Wei Li

.travis.yml

@@ -1,9 +1,9 @@
 language: node_js
 sudo: required
 node_js:
-  - 4
   - 6
   - 8
+  - 10
 services:
   - docker
 before_install:
@@ -21,9 +21,9 @@ matrix:
   include:
   # Include sync acceptance tests for node 4
   - node_js:
-      - 4
       - 6
       - 8
+      - 10
     services:
       - docker
     script: