FHIR integration is more specific than it need to be

[flyaruu]

At the moment, the FHIR integration pattern isn't constrained to FHIR, it basically works for any 'foreign' source.
It offers two patterns:

• Strongly typed. The integration supplies a type, and a parsing function byte[] -> T. Every source location needs to supply a T->Imessage function.
• Directly. A source simply supplies a byte[] -> IMessage function

[flyaruu]

Implemented genericSource, which takes a body parser
TODO: Also add optional key parser
TODO: Implement FHIR implementation on top of this implementation