john: Make package work out of the box.

So far it was only possible to run john if you've either copied over the
default configuration over to ~/.john and substitute $JOHN with the
right path or set $JOHN to the store path directly.

Both methods are not really a very good user experience, so we're now
patching in the resulting paths into the default rules/configurations.

This also splits off configuration files into $out/etc/john instead of
putting everything into $out/share/john and now also properly installs
the auxiliary programs into $out/bin.

Closes #8792.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
Reported-by: devhell <"^"@regexmail.net>
Cc: @offlinehacker