Clarify host name for system apps

[amcginn]

While SMART launch apps should be using the information in context to determine the FHIR server location, system apps typically are given the tenant ID to associate per domain in their system. This typically means the app has the host name "hard-coded" (actually or a "Cerner" default).

C1941/Ember (ec2458f2-1e24-41c8-b71b-0e701af7583d):

• http://fhir-ehr-code.cerner.com/<FHIR_version>/ec2458f2-1e24-41c8-b71b-0e701af7583d/

All other production domains:

• http://fhir-ehr-code.cerner.com/<FHIR_version>/<domain_tenant_id>/