test: add commitlint

Author: dominykas

package.json

@@ -7,7 +7,8 @@
     "url": "https://github.com/dominykas/allow-scripts.git"
   },
   "scripts": {
-    "test": "lab -L -t 100 -m 5000"
+    "lint-commits": "commitlint --from=${TRAVIS_BRANCH:-origin/master}",
+    "test": "lab -L -t 100 -m 5000 && npm run lint-commits"
   },
   "bin": {
     "allow-scripts": "./bin/allow-scripts.js"
@@ -20,6 +21,8 @@
     "topo": "3.x.x"
   },
   "devDependencies": {
+    "@commitlint/cli": "7.x.x",
+    "@commitlint/config-conventional": "7.x.x",
     "code": "5.x.x",
     "lab": "18.x.x",
     "mkdirp": "0.5.x",
@@ -31,6 +34,11 @@
     "bin",
     "lib"
   ],
+  "commitlint": {
+    "extends": [
+      "@commitlint/config-conventional"
+    ]
+  },
   "release": {
     "npmPublish": false,
     "tarballDir": ".",