Added compiler option to build the operating system timer stuff (using std::thread)
Moved the TestbedTime, TestbedTimer and TestbedClock into the libARA src (renamed)

Those implementations can be used in general whenever the real operating
system clock and threads should be used. Therefore I renamed the classes
to StandardTime, StandardTimer and StandardClock. I am still open for
other names though :)
Code cleanup of the StandardTime/r (former TestbedTime/r)