@mwpastore Could you rebase please?

cc #1216

@zzak I've noticed that we are reimplementing a lot of Rack::Response in Sinatra::Base::Helpers. I'm guessing this is due to the fact that Rack has improved over time to include more and more functionality. Can we use the delegation pattern to clean this up? Take a look at what I've done here. We can remove a bunch of tests, too, if we think this is a good idea.

There's a lot going on in this commit all of a sudden so let me know if you'd like me to break it up.

@mwpastore I'm not against using delegators but this close to a release -- I want to make sure this won't affect any behavior or have performance impact.

With that said, something like this could be investigated after the release is made.

Okay, I pulled the gnarly stuff out into a separate branch for later perusal and refocused this PR back to its original purpose. Let me know if you want to see any other changes!

For a second, I thought "body" was the body of the request, which would probably not be a good idea to print.

So can you change the wording from "body" -> "exception message"?

How's that?