Update the dependencies versions

- Require node 6 at a minimum to support the newer ES features.  Node
  version functionality determined via https://node.green.
- Update dev dependencies to their latest versions.  Mocha 3.4 relied
  on a version of growl with a known vulnerability.
- Fix the keywords section, this field is actually an array.
- Update eslint syntax to ES6.

.eslintrc.js

@@ -7,5 +7,8 @@ module.exports = {
   plugins: ["prettier"],
   rules: {
     "prettier/prettier": "error"
+  },
+  parserOptions: {
+    "ecmaVersion": 6
   }
 };