Add support for detecting Coffee Lake i[357]s. Test included.
Thanks to @X0rg for reporting and to @exdeus for the raw cpu data.
The detection here relies on Kaby and Coffee lakes having different
number of cores for the equivalent brand:
i3: 2 cores in Kaby, 4 in Coffee
i5 and i7: 4 cores in Kaby, 6 in Coffee.
