Remote-Remote File Transfer

Created by: osbornjd

This PR implements the capability for remote to remote file transfers to occur through the API, where the remote hosts are different (i.e. a transfer from remote host B to remote host C from local host A which is running Commands). One could also implement a command which runs a script that contains the logic to do this, i.e.

#!/bin/bash
scp -i /path/to/key someFile.txt username@hostname:/new/path/on/host/

The result is identical - but it is perhaps easier to call the file transfer through the Commands API.

Tests are ignored by default for the moment because of the lack of a second dummy host to test on. However tests pass locally and on windows when the proper key configuration is setup.