[PATCH] set response line (no replies)

Hi,

I'm submitting a patch that allows rewriting the HTTP response status code
and reason phrase.

There are two new keywords in 'http-response' that allows you to rewrite
them in the native HAProxy config. There are also two new APIs in Lua that
allows you to do the same rewriting in your Lua script.

Example:
Use it in HAProxy config:
*http-response set-code 404*
Or use it in Lua script:
*txn.http:res_set_reason("Redirect")*

Best,
Bowen