v1.2.0 - Better Null Handling

Some things changed in the Fireboard APIs (or maybe I just didn't read them well enough when I was creating this integration the first time).

• Upgraded the device retrieval method to ensure more accurate data about the device (mainly impacts the battery and rssi readings)
• Upgraded the channel temperature methods to ensure more accurate temperature data by actually reading the temperature endpoints instead of the device_log endpoints. This ensures more real-time data instead of historical data.

Full Changelog: v1.2.0...v1.2.0