Make accept header json when it was wildcard

[gepbird]

No description provided.

[gepbird]

When some applications send API requests (tested with Python's request module and Postman), they put a wildcard accept header(Accept: */*), not triggering this middleware. This PR makes it so every wildcard header gets converted into application/json.

[joskfg]

Thanks for you PR. I was reviewing the Accept header options and it seems it can produce things like:

Accept: application/json

Accept: application/*

// General default
Accept: */*

So, Could you include application/*?

[gepbird]

I made a commit for your suggestion, any updates?

[gepbird]

Any updates?

[joskfg]

Sorry @gepbird, I missed this. I think it is worth it to be added, so we will integrate the change. Thanks for your contribution.