Upgrade varnish

Upgrades the varnish_frontend recipe to use latest Varnish available in EY portage tree (3). Removes old varnish cookbook because who's honestly going to use 2.x anyway nowadays? Also changed varnish_frontend to do math on CPU and memory size in /proc to specify variables instead of hard-coding them in a switch/case thing because hard-coding it is bad, mmmmkay? Mmmmmkay.