Prevent crashes in http-proxy

This closes #1921.

`connect-restreamer` is fundamentally nuts and rather fragile. It also
makes no sense when we can just avoid the issue entirely by putting
`http-proxy` ahead of `bodyParser`.

People who have already run the proxy generator probably need to be
warned that they won't benefit from this bugfix.
Merge pull request #2568 from ef4/proxy-fix

Prevent mangled POST bodies in http-proxy