Ensure export reports progress

If a hadoop task does not either write output or reports status for 10 minutes it is killed. Make sure we check back in periodically with hadoop to ensure it doesn't kill our export processes.

@brianhw @rocha
I see -- so the problem here was that there wasn't a copy here, so it was actually appending to org_config['recipients'].  Presumably there's no difference between using set and list here.  If we really wanted to be careful, we could also check if gpg_master_key were already in the list of recipients below before adding it.  We could also use get('recipients', []) in place of org_config['recipients'], so that it handles having no recipients.  (That way it's only exported to the master key.)