mod_callcenter: Add tiers rules before jumping to a different level.  Also added support for dial-in agent.

"skinny profile internal device <tab>" now works

Thanks to Sergio

mod_sofia: Add a quick fix for basic Polycom presence support.  A more sane solution need to be implemented

add last_bridge_to var to keep uuid of last bridged channel and fix race in show calls on hangup of bypass_media channels