[PrinterDriver] Renamed _send to send! to reflect ruby idioms.
[PrinterDriver] Fixed find/replace fuck up from last commit.
[PrinterDriver] Renamed _print to print! to be more ruby-ish.
[PrinterDriver] Renamed send_now variable of send function to priority.
[PrinterDriver] Renamed _readline to readline! to make it more ruby-ish.
[PrinterDriver] Renamed _listen_can_continue? to listen_can_continue?.