Drop node 4 and 5 from travis build

Author: Jyrno42

.travis.yml

@@ -1,18 +1,17 @@
 language: node_js
 
 node_js:
-  - "4"
-  - "5"
   - "6"
   - "7"
+  - "8"
   - "node"
 
 before_script:
   - npm run build
 
 after_success:
   - npm run coverage
-  - test $TRAVIS_NODE_VERSION = 7 && npm run coveralls
+  - test $TRAVIS_NODE_VERSION = 8 && npm run coveralls
 
 notifications:
     email: false
@@ -32,4 +31,4 @@ deploy:
       2eFZClyuJi/5nJ1fBBAenRS0PBqLg=
   on:
     tags: true
-    node: "7"
+    node: "8"

package.json

@@ -115,7 +115,7 @@
     "check-engine": "node node_modules/fbjs-scripts/node/check-dev-engines.js package.json"
   },
   "devEngines": {
-    "node": "4.x || 5.x || 6.x || 7.x || 8.x || 9.x",
+    "node": "6.x || 7.x || 8.x || 9.x",
     "npm": "2.x || 3.x || 4.x || 5.x"
   },
   "nyc": {