Add getInitStatus() method to all initializable types

[cosparks]

We should have some way of verifying that initialization is successful for connected Sensors and any other classes which encapsulate hardware communication.

Multiple inheritance with ConnectedDevice abstract class, or simply add _initialized field and getInitStatus() method to all Handleable classes.

[cosparks]

This is only for ease of debugging. Not super high priority.

[KevinZhiyuanDing]

[check-initialization-#134] branch references this issue.