The previous method was clobbering the JingleSession prototype,
preventing the creation of additional subclasses.

Depending on the type of browser within which the library is executing,
we take the decision how many times to call getUserMedia (e.g. once for
audio and once for video on Firefox). Upon getting a result of the
call, we used to perform similar browser type checks. I see this as
repetition of logic which makes it difficult to add new browser types
(e.g. React Native). Try to examine the result of the call to
getUserMedia and thus avoid re-checkign the browser type.

Jicofo is smart and can find any bridge with service discovery and/or
pubsub.