Add patientService interface and mock
Rename OPSlotController to RestService Controller

It isn't really op slot specific
rest: Require login for addOPSlot

This can't be done without login.
MockedPatientService: Fix bugs
restService: Add getPatients

This is needed otherwise doing registrations is impossible
restService: Don't use a default value for required fields

This makes no sense.
Implement 'real' patient service