resolves tj#754 add linter configuration to project

- add linter configuration based on StandardJS
- customize linter to fit with style of project
- update source to reconcile violations
- inherit using util.inherits; must be add top of file for node 4
- use npm 3 on node 4 in CI

.eslintrc

@@ -0,0 +1,9 @@
+{
+  "extends": "standard",
+  "rules": {
+    "eqeqeq": "off",
+    "one-var": "off",
+    "semi": ["error", "always", { "omitLastInOneLineBlock": true }],
+    "space-before-function-paren": ["error", "never"],
+  }
+}

.travis.yml

@@ -6,3 +6,7 @@ node_js:
   - "8"
   - "9"
   - "node"
+before_install: if [[ $(node -v) == v4* && $(npm -v) != 3* ]]; then npm i -g npm@3; fi
+script:
+- npm run lint
+- npm test