Allow location specific definition of MIME type mapping?

[gwolf-011235]

Nginx allows for custom mappings of file extensions to MIME types via directive: types One can also set the default MIME type via: default_type

Right now the MIME type mapping is fixed in the ResponseBuilder (creates a map on construction)

To make it variable we would need to

• [ ] update ConfigFileParser to also handle types, default_type
• [ ] integrate this mapping in ResponseBuilder