* Correction for a faulty condition
The current condition works for checking existence of the .sfs files on the local file system.
The proposed condition checks for the existence of the .sfs files on a remote server.
* Correction for NFS & NBD & HTTP boot
By default, Calamares searches for the .sfs files in the "bootmnt" directory.
When "copytoram==y" (relevant for NFS & NBD & HTTP boot), the .sfs files are stored in the "copytoram" directory.
The proposed code binds the "copytoram" dir with "bootmnt" so Calamares can "see" the .sfs. files.