Facility uses incorrect integer values

[dhsmith1001]

The Facility class uses integer values 0-23, multiplied by 8. This is incorrect, they are defined as 0-23. The time to multiply them by 8 is when calculating the Priority value, facility * 8 + severity, per RFC 5424 (https://tools.ietf.org/html/rfc5424#section-6.2.1).

[cyrille-leclerc]

Thanks for your PR