Fix a crash and a deadlock.

subscribers needs to be protected by a mutex to avoid corruption (this includes the portions of code to deliver audio/video data), however there was an issue adding a mutext here due to a deadlock.  Change it so we lock around those methods, and make it so we tear down our WebRTC connection *outside* of the lock.  This prevents deadlocking on shutdown.
Fix an issue in the basic example

The basic example was assuming the very first room it encountered was the correct room.  Instead, let's look explicitly for 'myRoom' so we don't break if there's other applications running on the server.
Merge pull request #202 from jnoring/master

Fix a crash and a deadlock.