Sniff mode patch V2

Hi Marcel,

I spend most of the day reworking the sniff mode patch.
I implemented both L2CAP and RFCOMM, and tested those two. They both
seem to work.
The layering violation is gone.
The setting is propagated from a server socket to its children.

I think i've seen the end of your first round of comments ;-)

Could you please review this patch and tell me what needs fixing ?

Regards,

Fabien