Fixed the usb_serial node so it now compiles.
Moved the previously split send_serial_data and receive_serial_data into a single message. Renamed files to use usb_serial instead of usbserial. Updated CMakeLists to actually refer to usb_serial and not motors. Fixed bugs.
Added Encoders and USB/Serial ROS nodes. Some of the functions in thesrc/<node>.cpp files are not fully functional yet.