Docker image now using GCC 8 and Alpine 3.9. Experimental parsing of YAML, although responses still return JSON-only objects.

Added

• Experimental parsing of YAML
• Postman collection for testing documentation requests

Changed

• Require CMake 3.12 (again)
• Docker image using Alpine 3.9, GCC 8 and ICU

Fixed

• Check for requests with invalid body
• Compilation with cluster disabled