release/v1.0.0

• launch command when ping fails.
• opt --hosts; default: "8.8.8.8 8.8.6.6 1.1.1.1 1.0.0.1".
• detect if network is reachable.
• opt --ping-opt, ping options; default: "-c1".
• opt --boot-time, seconds wait to check network after command; default: 5.
• opt --check-time, network check delay in seconds; default: 5.
• restart (send SIGINT signal) on network error.
• opt --keep-alive, run command on init and restart on command exit.
• opt -v -vv -vvv, show log.
• opt -q --quiet, hide stdout/stderr from subcommand.