util/ssh.py: SSHConnection.get_file() method doesn't support file names with special characters

[gulnazgarif]

The SSHConnection.get_file() method uses scp to transfer files from the exporter, which fails to correctly interpret file names with spaces and special characters (e.g. parenthesis). Examples of files names that cause issues: "test file.log", "file(01).txt".

One way to overcome this could be to add an option to use rsync.