Http, client: Provide high-level support for response decompression

**Issue by [jrudolph](https://github.com/jrudolph)**
_Tuesday Feb 10, 2015 at 14:24 GMT_
_Originally opened as https://github.com/akka/akka/issues/16813_

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See spray/spray#987

In spray, you could add a `decode(...)` clause to your pipeline to add support for a single decoder. As noted in the ticket it would make sense to provide also an automatic solution that tries all known decodes.

/cc @sirthias

Start with the referenced spray/spray#987 issue and the described pipeline decode(...) behavior. Clarify the expected high-level response decompression and automatic handling of known decoders from the issue discussion; done means the agreed client behavior is supported and verified by appropriate tests.

Written by the indexing model from the issue text.