The administration of the server is done using cli tools. So I don't
think that admin account and module is required. At least for now.
Note that this also remove `tbl_admin` creation in database migrate.
Since no release were made until this commit, the database migration
still in version 1. Manual removal database table for `tbl_admin`
is required on the existing running server.
Adding struct chan to run cron Process to stop the goroutine.
Moving db migration inside `fiber.IsChild` block
to avoid multiple execution migration script when in prefork mode.
Give additional time for graceful shutdown.
Since `tbl_cron` will contain a few rows (for now just 1),
cron list function call is not using any arguments.
This commit also remove cron http handler and endpoint.
