Fixed proxying pages with encoding other than utf-8

[asagajda]

Jacob, thank you for sharing great tool!
Take a look at my PR, that fixes broken encoding when trying to proxy pages with encoding other than utf-8.
You can reproduce problem by querying http://localhost:3000/https://newtimes.ru/rubrics/ as example.

[imjacobclark]

@asagajda Thanks for the PR, could you fix the failing tests and potentially add some for the new functionality?

I'll look to merge this then! Thanks.

[solo5star]

I am using this project to get instagram images (cdninstagram.com) through proxy. Instagram gave me a jpeg response but since the default encoding is utf8, irrelevant values (UTF-8 magic bytes) ​​are attached to the jpeg byte array. Therefore, the byte array must be preserved by setting the encoding to null. (encoding: null)

[imjacobclark]

This looks great, are you able to add any tests so I can get this merged?