1.0.0-rc.4 + Laravel 5.8 compatibility

✨ Improvements

• Compatible with Laravel 5.8 (34d8e48)
• Compatible with Carbon 2 (8dfa795)

🐛 Bug fixes

• Allow nbf claim to be in the future (b860a4c)

🎨 Other

• Increase generated secret key length in jwt:secret command to 64 characters (f72b8eb)