[KIO][Device notifier] Ask for close files

Idea is like this:

  1. Implement KDE dbus-daemon to inform user ask to umount some medium
  2. When user asks to umount medium, this daemon send a message to each registered in daemon app
  3. When user click umount, message to each registered app was send, and currently displayed text (list of app, which has files opened on medium) + information that umounting is under process
  4. When app close opened files, it sends reposnse
  5. When got response, KDE tries to umount medium again
  6. other registered apps behaves in similar way …
  7. When KDE daemon got last response, it try to umount again and maybe with success…

But:

  1. Some apps could deny to close files
  2. In this case, break procedure and show info, what happened