Merge pull request #185 from elnappo/master

fix #183, minor template change and email backend in dev settings
catch more query_ns exceptions. try update/delete even if query_ns failed.

it could be maybe the secondary DNS that failed for query_ns, so we can still try talking to the primary.
fix resolving to not add the service server's domain, but just "."
management commands sending emails: mark strings as translatable
management commands sending emails: translate texts for the email recipient
add registration_closed template
Merge pull request #186 from jluebbe/master

add registration_closed template