Launch process example

To Compile:

mkdir build
cd build
cmake -DHPX_ROOT=[path_to_HPX_root] ..
make

To Run:

launch_process_test --launch=[full_path_to_launched_process_test]
launch_process_parallel_test --launch=[full_path_to_launched_process_test]

launch_process_test2 and launch_process_test3 are the new ones that works by attaching continuation to processes to create a chain of three process back to back. The launch_process_test3 launches 4 of these processes at same time, which all have set of processes to follow.