added ios backgrounding support to match current android functionality

Add backgrounding support for IOS to match Androids implementation

See here for the restoration and preservation API.
https://developer.apple.com/Library/ios/documentation/NetworkingInternetWeb/Conceptual/CoreBluetooth_concepts/CoreBluetoothBackgroundProcessingForIOSApps/PerformingTasksWhileYourAppIsInTheBackground.html

We need to change very few things for basic support actuality.