registered_notify_template.pt: show login name instead of user id.

Normally this is the same, but this is not necessarily true when
using the email address as login name.
utf-8 is the only supported site encoding
use system random
prep
vb
Fixed undefined django_crypto.

This is only used when 'socket.gethostbyname( socket.gethostname() )' fails.
This probably only fails on Macs without a fully qualified domain name.
We might need to use socket.gethostname() + '.local' then.
But for now this works.
Preparing release 2.0.11
Back to development: 2.0.12