Use RSpec 3.
Upgrade to foobar 2.
Remove fuubar entirely
Remove RSpec monkey patching.
Use change expectation in hash examples.
Clean specs up a bit.
More spec tweaking.
Make rubocop happy
More spec changes.
More speccing.
Guess what!  More spec changes!
Use rspec3.
Add root finder and specs.

This finds the root of an item in a composite tree, simples.
Use root finder for UrlReferenceable.

This is a breaking API change, as it removes #child_url.
Rename is_orphan? to is_root?.
Further rename is_root? to root?.
Make Rubocop happy.
Remove #child_url.
Fix erroneous documentation.
Remove another #child_url.