Bug 1100921: add default camera used to telemetry reports

Added default camera used in loop in Telemetry reports.
This will not work well because _frontCamera will have "true" or "false" value and therefore defaultCamera is always going to be 'rear'. 
If it is a audio call we are going to register an incorrect value ('rear'), perhaps it would be better 'front' 'rear' and 'none'