Add watchdog for snap changes that take too long

[everactivetim]

• It should run and reboot the device if it detects a change is taking too long
• The timeout for changes taking too long should be configurable
• It should write out the all the existing and current change information to a JSON document, also configurable
• It should keep track of internal errors and also reboot itself if too many of those occur, also configurable
• Rebooting should be configurable
• It should avoid re-writing the changes document if not rebooting