Merge pull request #138 from curbengh/node6

chore: require node 8 or above

Author: segayuu

.travis.yml

@@ -8,8 +8,8 @@ cache:
     - node_modules
 
 node_js:
-  - "6"
   - "8"
+  - "10"
   - "node"
 
 before_script:

package.json

@@ -43,5 +43,8 @@
     "hexo-util": "^0.6.0",
     "moment": "^2.18.0",
     "swig-templates": "^2.0.2"
+  },
+  "engines": {
+    "node": ">=8.6.0"
   }
 }