Allow setting custom HTTP headers

[bdw429s]

I've had a couple people ask about this. The idea is to configure a server to send some custom HTTP header response for every request such as adding an X-Frame-Options to every request. I don't know if it's possible or easy, but there might be usefulness in being able to block (or unset I think it's called in Apache) certain HTTP headers that may have been set upstream in the request.

[denuno]

I ended up adding the cookie httpOnly and secure headers by hand. Pretty easy. We could do a header-set="List=Of,Header=Values" and header-unset="List,Of,Headers" perhaps?