chore: drop Node 6 support

Allowing for #1275

BREAKING CHANGE: Dredd does not support Node 6 anymore. Node 6 has a scheduled maintenance end on April 2019.

.travis.yml

@@ -33,10 +33,6 @@ jobs:
         - "pip install --user -r docs/requirements.txt"
       script: "npm run ci:docs"
 
-    - env: "JOB=node6"
-      node_js: "6"
-      script: "npm run ci:test"
-
     - env: "JOB=node8"
       node_js: "8"
       script: "npm run ci:test"

docs/installation.rst

@@ -73,20 +73,20 @@ Installing Node.js and npm
       - If you’re using `Homebrew <https://brew.sh/>`__, run ``brew install node``
       - Otherwise `download Node.js <https://nodejs.org/en/download/>`__ from the official website and install it using the downloaded installer
       - Make sure both ``node --version`` and ``npm --version`` work in your Terminal
-      - Node.js needs to be at least version 6
+      - Node.js needs to be at least version 8
 
    .. group-tab:: Linux
 
       - `Install Node.js as a system package <https://nodejs.org/en/download/package-manager/>`__
       - In case your Linux distribution calls the Node.js binary ``nodejs``, please `follow this advice <https://stackoverflow.com/a/18130296/325365>`__ to have it as ``node`` instead
       - Make sure both ``node --version`` and ``npm --version`` work in your Terminal
-      - Node.js needs to be at least version 6
+      - Node.js needs to be at least version 8
 
    .. group-tab:: Windows
 
       - `Download Node.js <https://nodejs.org/en/download/>`__ from the official website and install it using the downloaded installer
       - Make sure both ``node --version`` and ``npm --version`` work in your Command Prompt
-      - Node.js needs to be at least version 6
+      - Node.js needs to be at least version 8
 
 .. note::
    If your internet connection is restricted (VPN, firewall, proxy), you need to `configure npm <https://docs.npmjs.com/misc/config#https-proxy>`__:

lib/getProxySettings.js

@@ -15,8 +15,7 @@ const PROXY_ENV_VARIABLES = ['HTTP_PROXY', 'HTTPS_PROXY', 'NO_PROXY'];
  * https://github.com/request/request#user-content-proxies
  */
 module.exports = function getProxySettings(env) {
-  // can't use Object.entries() yet (Node 6 support)
-  return Object.keys(env).map(name => [name, env[name]])
+  return Object.entries(env)
     .filter(entry => PROXY_ENV_VARIABLES.includes(entry[0].toUpperCase()))
     .filter(entry => entry[1] !== '')
     .map(entry => `${entry[0]}=${entry[1]}`);

package.json

@@ -7,7 +7,7 @@
     "dredd": "bin/dredd"
   },
   "engines": {
-    "node": "^6.9 || >=8"
+    "node": ">=8"
   },
   "scripts": {
     "docs:lint": "sphinx-build -nW -b linkcheck ./docs ./docs/_build",