[TIZEN] Tag the audio stream as "browser" in pulseaudio.

Tag the audio stream as "browser" in pulseaudio so that all the streams
coming from the web will be considered as coming from the same
source and preempt the streams for example if there's a phone call
coming.

At the moment the full Murphy integration is not in the place due to some
integration issues with the main loop. But, once we have all the fixes in
place, we will directly connect to the Murphy's resource engine and start
receiving notifications when any another stream preempting the streams
tagged as 'browser'. This will make the Crosswalk fully resource-aware.