Support new iTerm2 syntax

[xijo]

Hello,

the following applescript command works for the latest iTerm 2.9.20160206

tell application "iTerm2"
  tell current session of current window
    write text "$cmd"
  end tell
end tell

Maybe there is a way to support it in a backwards compatible way, see https://www.iterm2.com/applescript.html

Thanks for your work,
Jo