[Symfony] add support to transfer tokenStorage (user info) to the worker

[dkarlovi]

Implementing #68, I've found the processor needs to have information which user ran the query (I'm using the Blameable Doctrine2 extension).

I've added this as a temporary hack in the implementation, but the real solution would be to have an extension which would transfer the current tokenStorage from the message origin to the processor. This way we could use other Symfony features (like authorizationChecker for example) in our processors as naturally as we would in the web app.

We coul probably also trigger some core Symfony event (like kernel.request?) to make other listeners run, but that would be a nice bonus: after having the user token in place, it's easy doing some of the stuff yourself.

[makasim]

PR is welcome