Bug fixes and improvements
- Checks for a null message before it drops QOS 0 messages.
- Truncates job status detail values if they exceed the 1024 character limit.
- Updates the bootstrap script for Windows to correctly read the Greengrass root path if that path includes spaces.
- Updates subscribing to AWS IoT Core so that it drops client messages if the subscription response wasn't sent.
- Ensures that the nucleus loads its configuration from backup files when the main configuration file is corrupt or missing.