Refactor OAuth application stuff

src/structures/ClientOAuth2Application.js

@@ -0,0 +1,26 @@
+const User = require('./User');
+const OAuth2Application = require('./OAuth2Application');
+
+/**
+ * Represents the client's OAuth2 Application
+ * @extends {OAuth2Application}
+ */
+class ClientOAuth2Application extends OAuth2Application {
+  setup(data) {
+    super.setup(data);
+
+    /**
+     * The app's flags
+     * @type {int}
+     */
+    this.flags = data.flags;
+
+    /**
+     * The app's owner
+     * @type {User}
+     */
+    this.owner = new User(this.client, data.owner);
+  }
+}
+
+module.exports = ClientOAuth2Application;