Issue #6 OSX support via paramiko and pycrypt

Fix for issue #6

These changes include paramiko and pycrypt as dependencies to the plugin and allow for navigation editing and saving of files on osx.

I have only tested OSX. I have not specifically modified the ability for this to work with putty. I have only wrapped commands for the different os's based upon os mode.

This is my first go at python so I am sure my convention has left something to be desired.

I had a little issue with the nature of navigation of directories via paramiko's interface so for OSX I have changed the behavior of entering a folder. If you do the folder list is replaced with only the new folders contents. I also added a .. menu option to allow navigation back up the directory chain.

One thing I am not sure of is I had some issue with pycrypt until I built it locally on my system. I don't know if that is something that needs to be done via os or just once as I am unfamiliar with how python binds things like this.

Let me now if you have any feedback.

Paul