Log Message:
Update ruby-net-sftp to 2.1.1.

=== 2.1.0 / 06 Feb 2013

* Added public cert. All gem releases are now signed. See INSTALL in readme.
* Remove self-require, it causes a warning in Ruby 1.9.2. [jbarnette]
* Allow for upload to use the filename of the local file by default [czarneckid]
* Properly handle receiving less data than requested. [thedarkone]
* Added option to create directory on directory upload [Pablo Merino]
* Remove a warnings in tests [kachick]