Add basic packaging

Initial packaging to install `arya` in a location that is __(hopefully)__ in your path and allow for easy uninstall and upgrades.  This also handles versioning in some simple sense.

Documentation can be improved next I guess.  I have an idea for installation of arya as an editable package too but I'm not sure if pip handles that with branches at the same time.  Although for editable install it would help if we had a fix from pip for their new subdirectory support and it would be even nicer if the subdirectory support was not isolated to editable installs.