Fix routing problem

[yen3]

Original issue: fastapiutils#154

Credit: WouldYouKindly https://github.com/WouldYouKindly

If we use class-based routing, the cbv causes the double routes.
WouldYouKindly solves the problem, but he does not the patch to the
repo. I really need the patch for my daily development so I copy his
solution to resolve.

If it causes anyone feels uncomfortable, I will delete my PR.

Sorry for the copy

[yairsimantov20]

is there any update for that pr?
would love to use that fix

[tnte]

Looking forward to this PR being accepted. Having the same issue.

[yuval9313]

It doesn't passes tests, so I first need to figure whats going on there,
If everything is fine i'll update

[zon7]

I think the first test failing should be /items? instead of /items/?

[Caindrac]

Any news on getting these tests fixed?

[yuval9313]

I was lacking the update, The new code create an issue where @router.get as decorator doesn't works which means:

1. The code was not forked properly
2. The new changes breaks this functionality

I can try to fix the fork so it won't drop the multiple routes functionality but I'm lacking the time so I don't know how much time it is going to take, anyway I'm starting it now

EDIT:
I had a look in the code and I can describe what is causing the error
by doing as WouldYouKindly PR suggesting, I am removing the unbounded router therefore the self parameter becomes required again
I think I can have it fixed by deducting the prefix from the routes pre-adding them but I'm not sure I really like this fix because it involves string manipulation which is both risky and not very easy to read (sometimes)