fix(Response) Fix for autodetect text mime types.

[wolfeidau]

The original code returned base64 content when https://github.com/gin-gonic/gin provided the following mime type application/json; charset=utf-8 for JSON.

This fix works based on my testing, interested to hear your thoughts on using the inbuilt mime package for parsing.

• Changed matching to allow for trailing encoding.
• Added a test case for the updated function.

[ravern]

+1

Had the same issue with this while using gores package.

Why didn't I check the issues earlier... Spent the last hour trying to figure out why Postman was displaying base64 text.

[tj]

lgtm thanks!