Modules installer

This is a simple modules installer (can't handle multiple files, or requirements yet)

It connects to http://jaspermoduleshub.herokuapp.com/

I added a `walk_packages` on `brain.py` so that modules can be installed in subfolders.
Does this really have to be a dedicated function? It's just a wrapper for `tempfile.mkdtemp()`. If we ever want to do something more complex, we can put this into its own function then (the functions beginning with underscore are internal, so no third party devs should rely on them).