* Fixes Elasticsearch to have consistent capitalisation everywhere
across the code and UI (except the config file unfortunately).
* Adds basic unit tests for Elastichsearch.
* Adds a Elasticsearch docker image to the Makefile to enable testing
the Elasticsearch feature.
* PLT-6472: Basic Elastic Search implementation.
This currently supports indexing of posts at create/update/delete time.
It does not support batch indexing or reindexing, and does not support
any entities other than posts yet. The purpose is to more-or-less
replicate the existing full-text search feature but with some of the
immediate benefits of using elastic search.
* Alter settings for AWS compatability.
* Remove unneeded i18n strings.
