remote server path bug fixed

well, below is my folder structure:

js/
  foo/bar.js

but when i deploied (from windows) to the server the folder structure is below:

js/
  foo/
  foo\bar.js

I have review the code and think the 'toFile' variable in [sftpPut()](https://github.com/thrashr888/grunt-sftp-deploy/blob/master/tasks/sftp-deploy.js#L87) should replace sep from local to remote, so i tried this and it work well. 

Maybe you should consider that!