build(commits): add commitlint

Add commitlint with the Conventional Commits configuration. It will
automatically run during CI builds, and installs a `git` hook to run on
commit message entry.

Author: Arcanemagus

.travis.yml

@@ -8,6 +8,11 @@ jobs:
     - stage: test
       node_js: node
 
+    # Check the commit messages
+    - stage: test
+      script:
+        - commitlint-travis
+
     - stage: release
       before_deploy:
         # Decrypt the git_deploy_key.enc key into /tmp/git_deploy_key