move app stuff from bepasty to bepasty.app, put metadata into bepasty, closes #20

use metadata from bepasty (see package __init__.py) in setup.py and
sphinx' conf.py, so version number, year, etc. only needs to be edited
at one place.

the app stuff needed to move, so it does not import a lot of stuff from
dependencies if we just want to get a little metadata for sphinx or setup.py.

we have no author_email (should be a mailing list?) yet, but sdist wants one.
therefore, I added myself as (package) maintainer, including maintainer_email.