chore: Add pre-commit hooks

 - commit-msg validate-commit-msg ensures commits adhere to semantic-release.
 - pre-commit npm t ensures tests pass before committing.

package.json

@@ -25,8 +25,16 @@
     "semantic-release": "travis-after-all && semantic-release pre && npm publish && semantic-release post",
     "test": "node test.js"
   },
+  "config": {
+    "ghooks": {
+      "pre-commit": "npm t",
+      "commit-msg": "validate-commit-msg"
+    }
+  },
   "devDependencies": {
+    "ghooks": "^1.0.1",
     "semantic-release": "^4.3.5",
-    "travis-after-all": "^1.4.4"
+    "travis-after-all": "^1.4.4",
+    "validate-commit-msg": "^1.0.0"
   }
-}
+}