Feature is approved

This is the stub that @bfairbanks1 and I discussed. I wrote tests to make sure that the CheckApproval returns a double when a valid ID is passed, or returns -1 when an invalid ID is passed. This is according to the planned API for the ApproveGuest module.

The idea here is that we will use the CheckApproval class to get whether a user is approved. When the ApproveGuest module implements their API, we will be able to replace it with their Service.