No option for customizing Elasticsearch port

[blarghmatey]

There is no option exposed for being able to customize the port used for communicating with Elasticsearch. This is problematic for example when trying to use the AWS managed Elasticsearch service, as it defaults to using the HTTPS port 443, rather than the ES default of 9200. This results in enigmatic timeout errors when attempting to run anything in Forum that communicates with the Elasticsearch service, even if the host parameter is passed an HTTPS URL.