Provide sane packaging along with installation instructions

Currently, the README defines a process by which the upstream library Dehydrated is committed directly to the project, but it is also part of the project as a git submodule. We need to nail this down and figure out how to package it. Which one do we choose?

There's also the Libraries module, Drush makefiles, and ..

Also:

12:04 < ergonlog1c> subtree merge should work, and provide an easy (enough) way to stay up-to-date with upstream, fwiw