[TASK] Adds an example how to add attributes.

[pfinkbeiner]

With that commit comes the ability to add a specific title and
description to an image directly while uploading them.

There is even more possible like adding links or alternative text or any
other already existing field in sys_file_reference table. Even
extending the sys_file_reference reference is possible and fill it up with custom
data. Just extend the FileReference model in your extension, assign your
content via the model setter in UploadedFileReferenceConverter and thats
it. Happy uploading.

[pfinkbeiner]

Well, I removed that obsolete mysql_real… and htmlspecial… stuff. I also wrote a fallback if the given values are empty it will act a more natural way and NULL will be stored in the DB. In TYPO3 backend you'll see the checkboxes only checked if it contains valid content.

Maybe the PersistentObjectConverter is the right way to store that additional attributes in more »extbase way«, but for know it should do the trick. I would really appreciate it to see such a solution implemented in the extension_kickstarter!