configs.paste: serve paste, imgur and cyberlocker through fcgiwrap
One python CGI (configs/paste/paste.py) replaces the htgen-paste,
htgen-imgur and htgen-cyberlocker handlers and the paste-form script.
Items keep their names and directories, so old links and the backups stay
as they are; systemd hands the directories to the new paste user. The
upload form now stores directly instead of posting back to p.krebsco.de.