refactor: drop node4 support

README.md

@@ -40,7 +40,7 @@ See in detail each of these [use cases](https://github.com/verdaccio/verdaccio/t
 
 ### Prerequisites
 
-* Node.js >= 4.6.1
+* Node.js >= `2.x` (4.6.1) | `3.x` (6.12.0)
 * `npm` or `yarn`
 
 Installation and starting (application will create default config in config.yaml you can edit later)

circle.yml

@@ -12,6 +12,7 @@ dependencies:
         curl -o- -L https://yarnpkg.com/install.sh | bash -s -- --version $YARN_VERSION
       fi
     - nvm install 6
+    - nvm install 9
 
   cache_directories:
     - ~/.yarn
@@ -26,6 +27,8 @@ test:
     - yarn run test
     - nvm alias default 8
     - yarn run test
+    - nvm alias default 9
+    - yarn run test
 deployment:
   production:
     tag: /(v)?[0-9]+(\.[0-9]+)*/

package.json

@@ -150,7 +150,7 @@
     "build:docker:rpi": "docker build -f Dockerfile.rpi -t verdaccio:rpi ."
   },
   "engines": {
-    "node": ">=4.6.1",
+    "node": ">=6.12.0",
     "npm": ">=3"
   },
   "preferGlobal": true,