Implementing HTTP 405 if HTTP method doesn't match with required by the route

[Drunpy]

This PR purpose is to meet RFC 7231 sec6.6.5 and #1224

[SergioBenitez]

It looks like the tests are failing due to a UI mismatch almost certainly caused by differing versions of rustc. Check that your nightly compiler is up to date as this is what the CI will use. Once it is, you should get the same failures locally.

[jebrosen]

CI has been failing on master (probably for a while, sorry) and I only got around to fixing it yesterday.

@Drunpy, if you rebase your branch on top of the latest master the failing ui-tests should start passing again.

[Drunpy]

Ready for review ✔️ @jebrosen

[jebrosen]

Drat, I should have looked at this earlier so I could notice the rustfmt. Thanks for keeping those in separate commits though - that should make it easier to separate those changes out again.

If I'm reading right, the bulk of the change is to have the router not use method as a filter when finding matching routes, and to instead handle method mismatch one level up in Rocket::route. The overall approach seems reasonable, but I only have a fuzzy understanding of the routing code and would prefer to have a confirmation from @SergioBenitez before doing a thorough review.

[SergioBenitez]

This is incredibly difficult to review with all of the formatting changes. Please resubmit a PR without any formatting changes to existing code, and if possible, follow the existing style where you can.

However, I'd like to note the following: at a very high level, I'm for this change. My concern is the performance impact that this will have. It's very nice to be able to filter by method: it means we use it as a prefix. We should not remove this from the router. At worst, we should simply iterate through all possible methods, checking to see if there's a match, in case no route was found. This means we take the performance hit only if there's no match initially.