Chef cookbook for docker

Only tested on Ubuntu 12.04

This cookbook only supports x86_64, since that appears to be the only platform on which docker is available for now.

The cookbook does its best to install the packages necessary to enable the aufs kernel module. Some kernels include it in the base kernel image, others require the linux-image-extra package. If the aufs module is not available, the cookbook will try to install the version of this package that matches the current kernel, as indicated by ohai attributes.

On certain ec2 images, the install fails while installing the libsqlite3-dev dependency. An apt-get update fixes this issue. A way to address this without leaking package manager updates into this cookbook itself is to include the apt cookbook in the run_list before this cookbook. (see the Cheffile and Vagrantfile here for an example)