Minor consistency fixes
Move entity class to backend package.

More refactoring needed to consolidate constant references.
Refactoring to remove model layer refs from backend/acl code.

Permission lookup methods are now on the accessor model and the
permission object has been simplified.
Migrate backend-related code to its own backend modules.

There remains some front-end clutter and much naming to fix.
Next up: move backend test stuff to backend module.
Move some backend test harness code to the backend module.

This is far from finished and complete. The intention is to make
each module (including test code) more self-contained. However, testing
the backend without usable models (as defined in core) is tricky (though
definitely not impossible.)
More test refactoring. Not yet ready for prime time.

Currently there is an issue where backend tests run (seemingly)
concurrently, which leads to address-in-use errors.

Ultimately the best solution might be to mock the backend.
Move all integration tests to the main module.

Otherwise there's a problem with parallel test execution (and ensuing
chaos) that I can't figure out how to fix.
Fix missing i18n keys (fixes #396)
Minor cleanup
Refactoring of the Solr response parser impls
Stick dir=auto on a couple of text field wrappers. Tentative steps to addressing #400
Part 1 of admin module refactor (aimed at addressing #412).

Moved all controllers to their own package, which enables them to
have a split routes file without being in a separate module. Folded
authority module into archdesc. Vocabs stuff to follow.
Part 1 of admin module refactor.

Move vocab stuff to archdesc module (with split routes).
Part 3 of admin module refactor.

 - Sever portal dependency on linking/annotation modules
 - Move everything from linking/annotation/archdesc into
   admin module with split routes files.
Part 4 of admin module refactor.

Fold adminutils into new enlarged but separately-routed admin
module. Do away with admin menu monstrosity.

Working on doing away with route registry horror.
Rationalising templates to move URL refs out of core module
Strip out routeRegistry and tidy core controllers
Cleanups and fixes to broken JS routes
Implement Ajax promotion and demotion of notes.

This required some changes to the generic Visibility controller to
allow for async and non-async usage.
Move (currently unused) persona login handler