Reimplemented DO::Timer using C++11 chrono library
Fix bug DO::HighResTimer in *nix
Cleaned test_Timer.cpp unit test.
Compilation fix for DO::Timer.
Renamed `wait` function to `sleep` in test_Timer.cpp
Renamed sleep to milliSleep in test_Timer.cpp
Merge pull request #17 from DO-CV/fix-core-timer-unit-test

Fix Timer class and unit test.