REM: removed an unused doublett function "printBits" in util.c

ADD:  added a new string helper function "sprint_hex_ascii" in util.c
ADD:  added "LF AWID BRUTE", a very simple bruteforce command for the awid commands.
      it takes a facility-code,  and iterates all possible 0xFFFF cardnum by sending sim command. It also uses the usb_poll function to stop the bruteforce on keypress and not leaving the pm3 device running the simulation.
the command implements the help parameter.