Allow a manually set remote address for a fake request

Provides a quick way to change the remote address for a fake request. I needed to simulate different IP-addresses for security-tests.
I think the consistency is worth it here. In particular, many users have IDEs with autocomplete and it's nice to type "with" and see all the things they can modify. As far as the framework is concerned, `remoteAddress` is just as much a part of the request as anything else. Also, I think the "remote" part is enough to convey that the request is coming "from" that address.