File counter for sftp and suppressRemoteErrors option for sshexec

Thanks for excepting my last push request. I've add two more small changes.

SFTP now outputs the number of files and folders transferred. This is taken from grunt-copy. You may wish to check I'm counting the directories in the right place in the code.

SSHEXEC added suppressRemoteErrors option, if set to true, these messages are only shown in verbose mode.

Dave.