Periodically check for new config file

[shawaj]

We should periodically have the miners check for an updated blessed block from the block-tracker and if theres a config newer than currently synced block they pull the new one and restart miner

Otherwise the block tracker only really works if you power cycle or its a new device just being turned on

[robputt]

No longer required.

[shawaj]

Will eventually move to watchdog https://github.com/NebraLtd/hm-watchdog