HTTP redirect filter doesn't work for some HTTP/1.0 and Proxy cases

During review of https://github.com/servicetalk/servicetalk/pull/233 we discovered some scenarios with HTTP/1.0 or when connecting to an HTTP proxy where redirect may not work:
- https://github.com/servicetalk/servicetalk/pull/233#discussion_r247293690
- https://github.com/servicetalk/servicetalk/pull/233#discussion_r247294114
- https://github.com/servicetalk/servicetalk/pull/233#discussion_r247295119

Start by reading pull request 233 and its three linked review discussions to understand the HTTP/1.0 and HTTP proxy redirect scenarios. No source files or tests are named; the work is done when those reported redirect cases are handled correctly.

Written by the indexing model from the issue text.