Adding the new AbstractStorageEventListener that will serve as a base for other listeners
Fixing some coding conventions and refactoring the listeners
Adding an S3 event listener to store files on S3
Adding a test for the S3StorageListener
Adding doc blocks and a test
Fixing the afterSave in FileStorage.php
Adding tests for the ImageHelper
Merge branch 'feature/event-refactoring' into develop

Conflicts:
	Event/ImageProcessingListener.php