Add support to retire OpenMRS Patients using FHIR

Add support to retire OpenMRS Patients by implementing support for the FHIR DELETE interaction.

Please refer to http://www.hl7.org/implement/standards/fhir/http.html#delete

If the OpenMRS API refuses to retire a Patient, it should return the status code 405 method not allowed.If the resource cannot be deleted because it does not exist on the server, the server SHALL return 404 (Not found). Performing this interaction on a resource that is already deleted has no effect, and should return 204.