Fix lifecycle issues

[supersat]

When the screen is rotated, Android restarts the current activity. This is somehow breaking the logging service, even though it claims to still be running.

[supersat]

Some of this has been fixed, but there's still a number of related issues to fix. For example:

1. The config tab is always selected when MainActivity is restarted (e.g., due to screen rotations).
2. The status and cells tabs lose their state when recreated. Ideally they'd pull this from the database.
3. When the ConfigFragment is recreated, it sets the values of the various toggle switches, triggering the corresponding onCheckedChanged callback, which initiates a cell_log restart.
4. The "Enable Scanning and Logging" toggle turns off when the screen is rotated, even though the service is still running.