This commit introduces maxscale::future, maxscale::packaged_task
and maxscale::thread that are modeled after C++11 std::future,
std::packaged_task and std::thread as described here:
http://en.cppreference.com/w/cpp/thread
The standard classes rely upon rvalue references (and move
constructors) introduced by C++11. As the C++ compilers we must use
are pre-C++11 that feature is obviously not present. The absence of
rvalue references is circumvented by implementing regular copy
constructors and assignment operators as if the arguments were rvalue
references.
In practice the above means that when one of these objects are copied,
the state is _moved_ rendering the copied object in default initialized
state. Some care is needed to ensure that unintended copying does not
occur.
