Docker on Gentoo

Finally got Docker running on my Gentoo desktop, after a couple of days of futzing with the kernel configuration. The most valuable information I found along the way was this blog post, which covered most of the kernel configuration. Small differences due to the passage of time: the main portage tree is at docker 0.7.1 and go 1.2 now. Small difference due to my following the path of least resistance: I built an AUFS kernel. Everything seems to be working smoothly, though I haven't pushed hard yet.