Highlights of changes:
* Changes to the database cause notifications via AMQP for clients (325)
* Pluggable search engines (317), including SOLR (353)
* API is versioned and packages & groups can be referred to by invariant ID
(313)
* Resource search in API (336)
* Visual theming of CKAN now easy (340, 320)
* Greater integration with external Web UIs (335, 347, 348)
* Plug-ins can be configured to handle web requests from specified URIs and
insert HTML into pages.
Minor:
* Search engine optimisations e.g. alphabetical browsing (350)
* CSV and JSON dumps improved (315)