#13 Add Xeon support

[Marcus Bointon]

Most people using cpufreqd are on laptops, wanting to conserve power. As yet there is no support for Xeon-class CPUs at all, even though they have similar power saving features, and waste billions of cycles heating up data centres all over the world.

Any chance we could have Xeon support? I can probably get sponsorship for it if that helps.