Add setup for package installation

[Guriido]

If one want to use the package as standalone, it may be useful to have an installation that also wraps the c++ code, and compile it during installation of the whole face3d package.

What do you think about it @YadiraF ?

(Note: using this installation, the user needs to comment out the sys.path.append('..') line in the examples, in order to call the installed package)