Storing this key in secrets.yml was a bad idea,
it would require users using HA setups to manually
replicate secrets across nodes during update,
it also needed support from omnibus package
* Revert "Generate Let's Encrypt private key"
This reverts commit 444959bfa0.
* Add Let's Encrypt private key to settings
as encrypted attribute
* Generate Let's Encrypt private key
in database migration
Vladimir Shushlin