Fix swagger console backslash redirect for aiohttp (thanks @pando85)

[dtkav]

Fixes #831

Changes proposed in this pull request:

• redirect ui -> ui/ for aiohttp

[jmcs]

Won't this introduce a mismatch between this endpoint and all the others?

[dtkav]

@jmcs good point. I guess the best path forward is to look into enabling this for all routes on aiohttp to make the behavior similar to flask?

[dtkav]

It turns out we have to manually add a redirect for this route specifically because AioHttp removes the trailing slash from the static_files route (ui/*).

See https://github.com/aio-libs/aiohttp/blob/master/aiohttp/web_urldispatcher.py#L1049

I'll also add the middleware for redirecting all other routes to trailing slashes.

[dtkav]

Note, this depends on #823

[dtkav]

Wow this was a real rabbit hole to go down. 🐰
It turns out that some clients will turn POST requests into GET requests on a (301|302|303) redirect!
This is working nicely now with 308 redirect (https://tools.ietf.org/html/rfc7538).

[dtkav]

I've also put in a PR with aiohttp to change the default redirect code to 308 in the normalize_path_middleware.
aio-libs/aiohttp#3578

[jmcs]

@dtkav can you figure out why the flake8 started failing?

[jmcs]

👍