support for uWSGI

* naive uWSGI fallback which spawns one thread per request and
  one thread per mail notification
* uWSGI backend which utilize queues and spooling to handle
  simultanous requests and mail notifications

This also fixes a bug where N concurrent POSTs on a new topic
failed for N-1 requests (db integrity error).
add uWSGI development ini

    $ mkdir mail
    $ uwsgi isso.ini
Merge branch 'feature/uwsgi'
add basic spam protection
hide reply button when it is not possible to reply
document app/dom.js
Merge branch 'feature/spam-guard'
add configuration overview