Missing option for `Implicit FTP over TLS`

[lmlynik]

Creating the UnsecureFTP assumes that the connection will be always "Explicit FTP over TLS"

    /**
     * Constructor for FTPSClient, using {@link #DEFAULT_PROTOCOL} - i.e. TLS
     * Calls {@link #FTPSClient(String, boolean)}
     * @param isImplicit The security mode (Implicit/Explicit).
     */
    public FTPSClient(final boolean isImplicit) {
        this(DEFAULT_PROTOCOL, isImplicit);
    }

val ftpClient = if (settings.secure) new JFTPSClient() else new JFTPClient()

There is no way to configure for Implicit FTP over TLS

It would be worthwhile to expose this setting via the UnsecureFtpSettings object.