removed the need for a routing file in the profiler

This PR simplifies the code for the profiler: having to register a route for a panel in the profiler is not really great. This is the only possibility in 2.0 and 2.1, but for 2.2, we can do better.

Be careful though as this PR cannot be merged as is in master as the code is only for Symfony 2.2.0+. I think we need to create a 2.1 branch first for the code compatible with Symfony 2.1, so that master can get some improvements that need 2.2.

See symfony/symfony-standard#470 for the original report (wich should be fixed in Symfony SE but only for 2.0 and 2.1).

What do you think?