Renamed the utils directory to common

CMakeLists.txt

common/CMakeLists.txt

common/Timer.cpp

common/Timer.hpp

common/Utils.cpp

common/Utils.hpp

common/UtilsTest.cpp

common/exception/Backtrace.cpp

common/exception/Backtrace.hpp

common/exception/CMakeLists.txt

common/exception/Errnum.cpp

common/exception/Errnum.hpp

common/exception/Exception.cpp

common/exception/Exception.hpp

common/exception/strerror_r_wrapper.cpp

common/exception/strerror_r_wrapper.h

common/threading/ChildProcess.cpp

common/threading/ChildProcess.hpp

common/threading/Mutex.cpp

common/threading/Mutex.hpp