Added outputstream setter for LogManager

Added outputstream setter for LogManager
Made output of log headers explicitly requested
Output of log headers also apply to file log.
    src/main.cpp
    src/util/LogManager.cpp
    src/util/LogManager.h
    src/util/LogUtil.cpp
Added unit tests for Log and LogManager

Added unit tests for Log and LogManager
    src/util/Log.cpp
    src/util/Log.h
    src/util/TestLog.h        (+)
    src/util/TestLogManager.h (+)