Fix anonymous access by removing the AuthenticationCredentialsNotFoundException

[chalasr]

Q	A
Bug fix?	yes
New feature?	no
BC breaks?	no
Fixed tickets	no
Tests pass?	yes

For now, we can't handle the case of no token found in request, so I revert a part of my previous #157.
The problem is that we can't know if the current request can be done anonymously.

@slashfan If you see any way to know if the current request can be authenticated anonymously or not (retrieve firewall config?), I could be able to add a check and throw the exception only if the request cannot be authenticated anonymously.

[slashfan]

This may be overkill but why not dispatch a "jwt not found" event and let the flow of the request continue ? It will only be dispatched on a jwt protected firewall so developers can listen to it only if they are interested.

[chalasr]

@slashfan Separate invalid token and token not found in two events was my first thought, but it seemed overkill while I was able to dispatch the JWT_INVALID event for the two.
Now I think you are right, that would be adapted to add a JWT_NOT_FOUND and dispatch it while letting the request continue (so keep the normal behavior and take the control of the Response).

I be back with the changes quickly!