add check coverage action

@arvanasse I told him it was okay to just implement it as so.  We could do our own validation, but I don't see it as completely necessary since it's a non-obvious business rule.  Also, Fusion today required zip code in all cases for some silly reason.  We're going to change that, but I'd rather just fix it in Fusion than have to come and undo some validation in the action on our end as well.

Simple presence validation is fine in most cases, but anything beyond that is probably unnecessary.

I could be convinced though.