Twi Wire Interface (I2C) Implementation for SAM3U

@author JeongGil Ko <jgko@cs.jhu.edu>

The implementations are based on the preliminary specifications.

- The internal address features are not enabled due to the fact that
  the T2 interfaces do not support these as parameters. It can be
  easily implemented with Hpl commands.

- Needs testing with onboard temperature sensor. The temperature
  sensor's address is 0x48. 
