Adds partial changes to write only key feature.
Adds read and write commands to data slots.
Adds debug around write.
Fixes always succeeding write bug.  Adds mac to write32.
Changes key slots 6 and 7 to required encrypted writes.
Updates signature for new write32.
Adds nonce command.  Resolves issue #17.
Adds copy buffer utilities and xor utility.
adds initial (broken) encrypted write feature.