[PATCH] Add support for getting and deleting queueing classes

[Jose Ignacio Naranjo]

I miss something for searching and deleting classes, as is already done 
with qdiscs. I simply 'translated' the qdiscs functions, but I don't 
know if there is another solution already implemented or even they work 
perfectly (I didn't stress the functions, just standard tests and they 
worked properly). If you want me to do more testing or change something, 
please tell me what to do.

It is my very first patch using git, so I hope everything is all right.

Regards,
JI