Get tests sort of running again. Simplify requires by using autoload.

Log specs still need to be redone.
Refactor all the tests to actually test a real proxy & backend server.

In the process, fix some newly uncovered bugs in the new proxy:

- Incorrect path being logged (path was being duplicated).
- Incorrect body and header sizes for chunked requests/responses.
- Incorrect request buffer handling when the body was partially on the
header chunk.
- Missing request IP address

In addition, the backend servers are now configurable, and configuration
can be defined in a YAML file.