High-level HTTP client support

**Issue by [jrudolph](https://github.com/jrudolph)**
_Wednesday Feb 11, 2015 at 13:54 GMT_
_Originally opened as https://github.com/akka/akka/issues/16856_

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# It would be convenient if akka-http would provide common high-level HTTP functionality similar to what a browser supports in its backend. This is a collection of all the things that would belong into this category. This is a metaticket and each subfeature has its own ticket.
- [ ] connection pooling and configurable request queuing (provided by host-level API #15681)
- [x] request-level API (#15906)
- [ ] automatic redirection (#15990)
- [x] automatic retry attempts (#16852)
- [ ] try different IP addresses on retries (#16827)
- [ ] HTTP proxy support (for HTTP: #16853, for HTTPS: #16153)
- [ ] authentication data store (#16854)
- [ ] cookie store (#16855)
- [ ] response routing DSL (#15909)
- [ ] request building should be polished and documented (https://github.com/akka/akka/issues/18550)
- [ ] optional: response decompression (https://github.com/akka/akka/issues/16813)
- [ ] optional: Add support for OAuth authentication #16857

This is a metaticket rather than a standalone change; review the unchecked subfeature tickets such as #15990, #16827, #16853, #16854, #16855, #15909, #18550, #16813, and #16857. Start with the selected subissue's requirements and repository guidance. Done means completing that subfeature and updating this checklist when its ticket is resolved.

Written by the indexing model from the issue text.