Introduce ssh.set_working_directory
Move prepending 'cd %r' into the ssh_channel after the command has been printed, to prevent cluttering the screen
Permit wd= arguments for run and run_to_end
No need for old_wd now that we "cd foo;" vs "cd foo &&"
Squelch output from bad working directories; set_working_directory shows a warning
Fix incorrect doc
Newline at OEF
Fixed up the pull request a bit