Make childCount a managed property, indicated with an underscore
Add an update-if-exists flag to EntityAdd cmd
Fetch mutation events by default
Start adding mechanisms to meaningfully compare bundles and only update if they differ
Add mechanism to update db instead of wiping
Cache the bundle hash to avoid traversals
Remove debug
Only validate if updating
Don't rely on a cached hashcode 'cos it could easily get invalidated
More work on idempotent updates.

 - the BundleDAO now returns a mutation object which contains a state
   and an object (instead of just an object). The state indicates whether
   the object was created, updated, or unchanged
 - All the relevant higher level APIs updates to use this
 - The REST interface does not yet indicate if an item was changed or not.
   Maybe we should add this in.
 - UkrainianRepoImporter and its command have been deleted because
   their jobs are done from the JRuby script now.
 - Still plenty of improvements/tests needed.
Fix totally broken getBundle(bundle, path) code and allow -1 index for insert
Add a dodgy equality test to check order is disregarded
Rename some bits and add some idempotency tests
Tweaks to ukraine import script
Minor fixes to build script
Changes to SKOS import.

 - Concepts now use a derived id instead of a UUID, which allows us
   to do idempotent updates. Currently it uses the last part of the
   URL section with is a hack.
 - Other minor tweaks
s
My changes to the SKOS importer totally broke building the relationships.
Clean up concept-related importer tests
Ignore 'managed' properties (i.e. caches, etc) in Bundle equality calculations.