CD: include requests break on unencoded query parameters #212

The CD resolver builds its downstream URLs without percent-encoding, so a space or non-ASCII character in a custom parameter or id fails the request with a 500. A decoded & or = in a value can also inject extra parameters, such as a different filter[id]. The fix encodes every client- or data-supplied part of the URL, and sends multi-valued parameters as repeated parameters. It also adds propagated custom query parameters to the resource cache key, so responses that vary by them aren't shared between callers.