If the dominant speaker leaves their object will be gone from the mapping.

There are modules that will not work with prosody 0.10 as they depend on util.async. Adds a safeguard and print error about it in the logs.
And others that just do not work because of the muc module API that they use.

* Correctly process speaker stats events when the conference contains a subdomain

Adds the component which receives the messages from client and a module which enabled on a virtual host will start advertising the component. When clients discover the component they will send message to the component with the name of the room where the dominant speaker event happen.