Error Management

Error Management for Audio.
Changed error 807 to RTSP error code (401)
Changed event names

Changed event names to audioTransmitStarted and audioTransmitStopped
Fixed wrong event name
Added audioTransmitStopped event to error 813
Fixed merge errors
Merge pull request #49 from LingoLasse/axistransmit

AxisTransmit: Audio Errors and events