Travis CI env updated with Elasticsearch 6

Author: ishakhsuvarov

.travis.yml

@@ -54,7 +54,7 @@ cache:
     - $HOME/node_modules
     - $HOME/yarn.lock
 before_install:
-  - curl -O https://download.elastic.co/elasticsearch/release/org/elasticsearch/distribution/deb/elasticsearch/2.3.0/elasticsearch-2.3.0.deb && sudo dpkg -i --force-confnew elasticsearch-2.3.0.deb && sudo service elasticsearch restart
+  - curl -O https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-6.6.1.deb && sudo dpkg -i --force-confnew elasticsearch-6.6.1.deb && sudo service elasticsearch restart
   - ./dev/travis/before_install.sh
 install: composer install --no-interaction
 before_script: ./dev/travis/before_script.sh