build(git): lint commits before creating them

Lint using Commitlint, running via Git hooks installed with Husky. This
was done with the following commands:

```shell
npm install --save-dev @commitlint/{cli,config-conventional}
echo "module.exports = { extends: ['@commitlint/config-conventional'] };" > commitlint.config.js
npm install --save-dev husky
npm pkg set scripts.prepare="husky install"
npm run prepare
npm pkg set scripts.commitlint="commitlint --edit"
npx husky add .husky/commit-msg 'npm run commitlint ${1}'
```

Lint within VS Code using the recommended extension in the .vscode directory.

Issues: #18

.gitignore

@@ -0,0 +1 @@
+node_modules

.husky/commit-msg

@@ -0,0 +1,4 @@
+#!/usr/bin/env sh
+. "$(dirname -- "$0")/_/husky.sh"
+
+npm run commitlint ${1}

.vscode/extensions.json

@@ -0,0 +1,5 @@
+{
+    "recommendations": [
+        "joshbolduc.commitlint"
+    ]
+}

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "cSpell.words": [
+        "commitlint"
+    ]
+}

commitlint.config.js

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