debian: synchronize debian/control with upstream packaging
debian: synchronize debian/copyright with upstream packaging
debian: ship a commented-out cron file instead of an example
debian: ensure rancid shell is /bin/bash

This is needed to make various tasks work as user rancid without getting
root. Details are here:
 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=654353
debian: also conflicts with par package

rancid ships its own "par"
debian: update translation files (sync with upstream packaging)
debian: remove all debconf warnings

Those warnings are saying that the packaging is experimental and that it
is possible to lose data. There is nothing in the packaging which will
erase any data and the warnings are quite old.