Fixed deadlock when calling dispose when Initialize is not completed

[terziman]

This fix is designed to solve the deadlock observed when dispose is called but Initialize method has not yet completed. It happens in async apps if the OBD device is not plugged for example.

[DarthAffe]

Hey, thanks for contributing. This issue should be one of the cases handled in #24. For some reason I thought it was already merged but it seems like I forgot to actually do it.