Brookstone AC13 Rover added
Source files refactored
 - Loggable class added to avoid dependencies to android.util.Log
 - BaseRobot class added, all Robot classes should inherit from BaseRobot class (or DifferentialRobot)
 - NXT and Dotty inherit from DifferentialRobot
 - interface classes renamed to start with I..
 - unused classes removed
 - unused imports removed from class headers