[xmonad] Newbie first patch to make the **Ssh** extension work with user.

Hi, The patch add *user* support to the *Ssh* extension, .e.g ssh admin@host. By the way, it is the first time i write haskell code snippet for a great project. If there is anything wrong with the code, code style, comment, please let me know. The *XMonad* is awesome, i love it. -- No pain ,No gain!

From Ray!