Re-evaluate the high performance bus manager research project

[EdHurtig]

The bus_manager was a performance optimization that offloaded all I/O operations onto separate threads for each hardware bus (I2C, SPI, Serial, etc.). This project was sidelined for CW2, as were a lot of other projects, but now is a good time to bring it back and get it integrated to see if it makes any difference.

[EdHurtig]

Initial Design Doc https://docs.google.com/a/hurtigtechnologies.com/document/d/1Qfu5BLMy4eLoYS1mhtnzRv026lc4IdRW3gWWOXSDmqc/edit?usp=sharing