Add traps; user registration

app/routing/middleware/util/Setting.middleware.js

@@ -0,0 +1,19 @@
+const { Middleware, HTTPError } = require('libflitter')
+
+class SettingMiddleware extends Middleware {
+    static get services() {
+        return [...super.services, 'models']
+    }
+
+    async test(req, res, next, { key, value = true }) {
+        const Setting = this.models.get('Setting')
+        const actual_value = await Setting.get(key)
+
+        if ( actual_value !== value )
+            throw new HTTPError(404)
+
+        return next()
+    }
+}
+
+module.exports = exports = SettingMiddleware