Stub for c++ was added, interface changes.

Stub for c++ was added. It now allows us to use the service from c++ code.
CMake fixed, not only binaries but headers are installed too for 'install' target.
Headers and source files went to include and src directories.
Interface of get function changed. It now returns tuple and accepts one more frequently used parameter cookies.
Logging added to the service.

Breaks compatibility with previous versions but as I can see noone has been using it yet.