Remove support for old nodejs versions

Author: euank

.travis.yml

@@ -1,13 +1,8 @@
 sudo: false
 language: node_js
 node_js:
+  - "10"
+  - "8"
   - "6"
-  - "5"
-  - "4"
-  - "3"
-  - "2"
-  - "1"
-  - "0.12"
-  - "0.10"
 before_install:
   - "npm install npm -g"