all responses are assumed JSON

Given Swagger:
```
swagger: "2.0"
info:
version: ""
title: test
schemes:
- http

paths:
/fragment:
get:
produces:
- text/html
description: returns some html
responses:
200:
description: text/html response
schema:
type: string
```

HippieSwagger 3.2.0 chokes on the response, as it assumes *all* responses to *always* be JSON - but can't parse HTML as JSON. Can the JSON-parsing be disabled somehow?

Specification for Swagger 2.0 concerning mime-types in requests and responses:
https://swagger.io/docs/specification/2-0/mime-types/