Fix migration issue on settings page

Re: http://manage.dimagi.com/default.asp?89710#515034

The expectations for the commtrack config object changed during @mrgriscom 's work. I don't know if this PR is the right way to fix this, though.

https://github.com/dimagi/commcare-hq/compare/commtrack-makethehurtingstop#diff-463c131ae3bff84c5e5063a90277afd7L71