(doc) Updated benchmarks for newest results.

This also adds new benchmarks for the Server and mocking the Clients.
(doc) Documented the internal design of Hyper.

This includes a rationale and description of the overall design of
Hyper as well as providing a guide to understanding and navigating the
source.
Move internal design overview to documentation, add examples to README

While the README examples are not checked by rustdoc, they are important
to have as they show-off hyper to the world :)
Merge pull request #46 from reem/enhance-README

(doc) Documented the internal design of Hyper.
Fixed bad reference to echo server example.