UploadManager: Managing uploaded files via Web forms

UploadManager is a class for manipulating files uploaded to a server via Web forms: It can:

* Access the files upload to the server
* Store the files in a specific folder
* Delete exising files
* Prepare the listing of uploaded files

This class also has these features:

1. Delete or reate the directory to store uploaded files
2. Create, modify or delete the uploads directory index file (by default, 'index.html')
3. Create, modify or delete the file with descriptions of the uploaded files (by default, 'files.bbs')