Ilsgateway integration

@czue I moved changes from ilsgateway-products-integration to this branch and I added webusers integration. I will be pushing all integrations with ilsgateway in this branch.  Is it ok? I assume that you don't want to merge this changes until it will be completely done?
@czue For now I'm using something that you describe but for whole commtrack settings. 
```Python
    @property
    @memoized
    def commtrack_settings(self):
        # this import causes some dependency issues so lives in here
        from corehq.apps.commtrack.models import CommtrackConfig
        if self.commtrack_enabled:
            return CommtrackConfig.for_domain(self.name)
        else:
            return None
```
So should I consider using something similar but for particularly for ILSGateway config?