Update Elasticsearch version used on Codeship and Travis-CI

Description

We're running Elasticsearch 6.2.4 on production and should be using it on Travis and Codeship as well.

Testing
Nothing to test

Environment

None

Assignee

redsummernight

Reporter

Sarken

Roadmap

Search

Priority

Medium

Affects versions

Fix versions

Components

AutomatedTests

Difficulty

Easy

Required Access Level

None

Epic Link

Milestone

Internal 0.9
Configure