Undefined Scope Index Fix

*This fix will allow undefined index handling...i.e. when onboardingSteps load
asynchronously and scope index is not yet available.

*Example:

*Say you have a factory, OnboardingFactory, that loads the steps.

		$scope.onboardingEnabled = false;

		OnboardingFactory.getOnboardingSteps().then(function(steps){
			$scope.onboardingSteps = steps;
			$scope.onboardingEnabled = true;
			$scope.onboardingIndex = 0;
		});

*Check index watch newval is undefined instead of === null to allow for this.