[HAO-Tracker-2014-Primary] Update main.cpp wrt Logger lib refactoring

- As Logger library no longer includes SD wiring and initialization
code, the related code has been moved to main.cpp in initSD internal
function
[HAO-Tracker-2014-Primary] Update main.cpp wrt Logger lib refactoring

- As Logger library no longer declares a singleton instance but a
constructor, main.cpp has been modified in order to take this
refactoring into account