Add default responseData

[ailiao]

Add default responseData so that empty response bodies like for status code 204 don't result in UNIHTTPClientHelper.m returning a nil UNIHTTPResponse

[AleksandarLugonja]

Can someone please review and merge this? When included into Fuse application, this library crashes on status code 204 responses all the time.

[CLAassistant]

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❌ Evgeny Gushchin
❌ ailiao

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