Update README.md

New Middleware method signature now that Alloy moved into Request
Merge pull request #33 from brycefisher/patch-1

Update README.md
(cleanup) Tidy rust-url usage, restore old API.

Restore &str route API and clean up usage of rust-url.
Merge pull request #32 from michaelsproul/cleanup/rust-url-usage

(cleanup) Tidy rust-url usage, restore old API.
(feat) HTTPS for rustup
Merge pull request #34 from brycefisher/patch-1

(feat) HTTPS for rustup
(fix) Update for new iron::Url API.

Also, restore `rust-url` non-empty path invariant.
Merge pull request #35 from michaelsproul/fix/url-api-update

(fix) Update for new iron::Url API.
(fix) Alloy -> Extension change.

And update `ImmutableEqVector` -> `ImmutablePartialEqSlice`
Merge pull request #36 from michaelsproul/fix/extension-update

(fix) Alloy -> Extension change.
(fix) Update for extensions changes.

Fix double mounting.