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.

test/.eslintrc.js

@@ -1,5 +1,8 @@
 module.exports = {
   env: {
     mocha: true
+  },
+  parserOptions: {
+    "ecmaVersion": 6
   }
 };