build(git): enable commitlint

Add a configuration for `commitlint` that enforces Angular-like commit
messages in preparation for adding of `semantic-release`.

.travis.yml

@@ -1,5 +1,7 @@
 ### Project specific config ###
-language: generic
+language: node_js
+node_js:
+  - "8"
 
 env:
   matrix:
@@ -9,6 +11,9 @@ env:
 os:
   - linux
 
+before_script:
+  - commitlint-travis
+
 ### Generic setup follows ###
 dist: trusty
 

commitlint.config.js

@@ -0,0 +1,5 @@
+module.exports = {
+  extends: [
+    '@commitlint/config-conventional',
+  ],
+};

package.json

@@ -43,11 +43,18 @@
     "resolve": "^1.5.0"
   },
   "devDependencies": {
+    "@commitlint/config-conventional": "^5.2.3",
+    "@commitlint/travis-cli": "^5.2.8",
+    "commitlint": "^5.2.8",
     "eslint": "^4.14.0",
     "eslint-config-airbnb-base": "^12.1.0",
     "eslint-plugin-import": "^2.8.0",
+    "husky": "^0.14.3",
     "jasmine-fix": "^1.3.1"
   },
+  "scripts": {
+    "commitmsg": "commitlint -e $GIT_PARAMS"
+  },
   "eslintConfig": {
     "rules": {
       "global-require": "off",