Input type doc

• Ignore mime-types accept for GET, HEAD and DELETE operation docs
  • We'll probably revert this eventually
  • Check this out: https://github.com/OAI/OpenAPI-Specification/pull/1937
• Add accepted mime-types to operation doc
• Add request type filtering to readme
• Add default permissive request body description to doc generation
• Fix unknown type "as-is" on cli options
• Move accepts type parsing to own file
• Update test suite to listen based on a constant instead of explicit 'localhost'