Merge pull request #352 from davidbuzz/auth

break out OTP library from auth.c into otp.c/otp.h
remove otp code from auth.c - see otp.h for new location.
* rework otp functions in systemlib so the "write" function/s actually work.     also rework auth.c to use this code, and two new  flags to the 'auth' command:  -m and -d
-m  means  make a public key file on SD card at /mnt/microsd/publickey.txt from the private key
-d -means dump Hardcoded Private/Public Keys onto SD card

TODO  - just need to test and implement -k code.   everything else is great!