Refactor EEPROM Implementation

[ericyanush]

The current eeprom management class is very tough to maintain; it is full of "magic numbers" and its storage schema is hardly obvious. It makes understanding the current eeprom size utilizatio, and adding/removing/changing fields difficult.

Refactoring the implementation to use either a C struct or a POD C++ class stored directly using the EEMEM attribute. One issue with this, is the bootloaders used on BrewTrollers doesn't implement the ability to flash the eeprom directly, so it needs to be initialized and managed in code.