ScpClient.Upload(DirectoryInfo, string) adds extra directory level

When using the ```SCpClient.Upload(DirectoryInfo, string)``` overload to upload the content of a directory to an SSH server, an extra directory level is created for the last part of the remote path.

For example:
when the remote path is **/home/sshnet/test**, then the local files (and subdirectories) will be copied **/home/sshnet/test/test** instead of **/home/sshnet/test**.