Stop shelling out to scp

[geelen]

At the moment, we write a temporary file then shell out to scp to upload it. It's dumb.

Use Net::Sftp or something instead.

[lparry]

I've got a patch for this on the branch use_sftp_for_file_writes

the downside of this patch is that shell expansion doesnt work with it. ie. '~' and '$HOME' dont get expanded. if you give an absolute path it works great.

a possible solution might be to use the ssh session to expand the path on the remote system prior to passing it to net::sftp