Account for multiple scenarios in onScenarioStart
Merge pull request #122 from virtual-world-framework/fix-scenario-loading

fix-scenario-loading
Cleaning up YAML to remove unnecessary sound properties
Rover voice changed to male
Created rover sounds layered sound definition.
Attempting to abstract away stopping sounds with no instance ID
Wind and gameplay play on start again.
Hacky way to stopSound using triggers by retaining sounds in the soundManager
Added trigger-based failure and low-battery failure sounds.
No need to provide sound instanceID anymore. Will stop all sounds if only soundName is provided.