Remove uppercasing of default HTTP Status reasons

Remove uppercasing of default HTTP Status reasons

If you do `return Response("foo", "404 Not Found")`, the status line will be `HTTP/1.1 404 Not Found` as expected.
If you do `return Response("foo", 404)`, the status line will be `HTTP/1.1 404 NOT FOUND`. (which is obviously fine as far as the protocol is concerned, just not consistent, necessary or usual)

Originally from commit 85e43c12fd74375779d23c117594ea325b944d8c
https://github.com/mitsuhiko/werkzeug/commit/85e43c12fd74375779d23c117594ea325b944d8c
(That's probably coming out of nowhere, since this was over 5 years ago)