add the aufs3-loopback patch, and update to latest 3.15.10 kernel

this seems to stop #425 from happening for me.

and may well help with https://github.com/docker/docker/issues/7341.
we'd still need to patch it - that tree doesn't have the `aufs3-loopback.patch` applied.

I have no arguments either way - personally, I do like how we're using the kernel.org kernel and then explicitly showing what we are changing.