Add alarm checks for block count lag and service down

[gokr]

Checking and comparing block count regularly with other prominent nodes to detect if we are lagging severaly. Checking that nano_node is up, and also canoed, redis, postgres, vernemq, nginx. Make some RPC calls to make sure everything works.

[stefonarch]

Lagging often is no issue for transactions. Many monitors have this api.php I use here: https://nanode21.cloud/nodestats.htm