Ilsgateway bugs

@czue I fixed this bug: http://manage.dimagi.com/default.asp?134684#755968

Also I've changed a little bit checkpoint functionality. I've added table to ILSGateway config view to follow status of checkpoint. Could you merge this with staging?

@millerdev For now it's only used for enabling ILSGateway migration in commtrack(from UI). Primarily ILSGatewayConfig was in commtrack models in corehq but Cory want to move this to custom module. Do you have any suggestions how to solve this better?
@czue Maybe you have some suggestions?
Line below will be removed because we switch ils task to periodic task eventually. 
Btw. similar situation here: https://github.com/dimagi/commcare-hq/blob/master/corehq/apps/locations/views.py#L24