Fix broken maxFilesQuantity property of rich:fileUpload component

1. create a File
2. click the Files tab
3. add 8 files
4. the default property maxFilesQuantity limits this to 5 (by default) and only shows 5 files ready to upload
5. notice the button Add is not disabled
6. click Add button and select a file
7. the file is added to the list and the limit is not enforced

This looks like opened bug from RichFaces:
https://issues.jboss.org/browse/RF-12366