The sample application that you can download to install Vulnero includes both the core functionality and a sample Zend application. The core Vulnero components required to function include only a single file and a single directory:
wordpress-plugin.php
Contains special docblock to tell WordPress it's a plugin. It includes the name, url and version shown in the WordPress plugins panel. It's also the application's entry point which configures some constants, autoloading, and loads your application.
library/Vulnero
Directory containing all of Vulnero's functionality, including all of the abstract classes and interfaces you'll need to interface with the WordPress API.
The remaining files and directories included in Vulnero's distribution are simply defaults for a module-less Zend Framework 1.x application, created so you can start developing routes and functionality as quickly as possible. You're not restricted to this structure. The structure of the application directory and most of the configuration is completely flexible.