remove UseControllerWorker

I came across issue with assetic `cssrewrite` filter not working correctly, Basilcy similar case like in this issue https://github.com/symfony/AsseticBundle/issues/90

So my solution was to add my custom `assetic.factory_worker` that removes `_controller/` from `targetPath`.

And with it everything seems to work fine. `cssrewrite` filter now change paths correctly in `dev` environment with `use_controller` enabled, `assetic:dump` command still works fine so i stared to digg more to find wher `_controller/` prefix have some application and I couldn`t find any. I assume that this is some relic after some old routing for `use_controller` option. 

I did some more testing after removing this worker from `AsseticBundle` and I also could not find any case where it breaks something. Mayby there is some usecase for this worker that i'm not familiar with but from my tests it looks like it is useless and only mess up `cssrewrite` filter so I suggests to remove this worker.