Ticket #2923: broken aliases in SFTPFS.

(sftpfs_correct_file_name): fix handling of tilde-starting file names.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>
Fix: sftp: password ask too often if hostname was bring from ~/.ssh/config file

Signed-off-by: Slava Zanko <slavazanko@gmail.com>