Since the updated RFC 7230 implys that new Headers Key and Value should be
sent as USASCII only don't try to test utf8 headers in examples.
We now only encode them to ascii. Gunicorn will fail if it's unable to encode
them letting the responsability to the application to correctly encode the
response. (we are just a gateway).
While i'm here simplify the code to not create an extra function only used at
NOTE: if anyone come to a better solution, i am happy to revisit it on the