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?
@gcapalbo @czue I think about solution that you've described above but there is one problem. For some keywords we need to execute handler from commtrack and also do some other operations specific to ILS. Maybe we can execute commtrack handler from ilsgateway handler for some specific keywords. Do you have some suggestions?