Log Message:
Update ruby-net-ssh to 2.8.0.

=== 2.8.0 / 01 Feb 2014

* Handle ssh-rsa and ssh-dss certificate files [bobveznat]
* Correctly interpret /etc/ssh_config Authentication settings based on openssh \ 
/etc/ssh_config system defaults [therealjessesanford, liggitt]
* Fixed pageant support for Windows [jarredholman]
* Support %r in ProxyCommand configuration in ssh_config files as defined in \ 
OpenSSH [yugui]
* Don't use ssh-agent if :keys_only is true [SFEley]
* Fix the bug in keys with comments [bobtfish]
* Add a failing tests for options in pub keys [bobtfish]
* Assert that the return value from ssh block is returned [carlhoerberg]
* Don't close the connection it's already closed [carlhoerberg]
* Ensure the connection closes even on exception [carlhoerberg]
* Make the authentication error message more useful [deric]
* Fix "ConnectionError" typo in lib/net/ssh/proxy/socks5.rb [mirakui]
* Allow KeyManager to recover from incompatible agents [ecki, delano]
* Fix for "Authentication Method determination can pick up a class from the \ 
root namespace" [dave.sieh]