Completed bot_mk1 implementation.

Task @T49 : This checkin completes the bot_mk1 implementation pending
unit tests. All new and overridden methods are complete and compile
cleanly. Ready for unit test development.
Removed as_str() override from bot_mk1.

Task @T49 : as_str() was mistakenly left in bot_mk1.h. Removed as
there is no current reason to override the default behavior.