Elasticsearch 7 support 🚀 (#760)

* API generation

* Updated typings

* Updated code generation

* Updated test

* Updated ci configuration

* Fixed test

scripts/es-docker.sh

@@ -5,8 +5,10 @@ exec docker run \
   -e "node.attr.testattr=test" \
   -e "path.repo=/tmp" \
   -e "repositories.url.allowed_urls=http://snapshot.*" \
+  -e "discovery.type=single-node" \
   -p 9200:9200 \
-  docker.elastic.co/elasticsearch/elasticsearch:6.5.0
+  docker.elastic.co/elasticsearch/elasticsearch:7.0.0-alpha2
+  # docker.elastic.co/elasticsearch/elasticsearch:6.5.4
 
 #  -e "xpack.security.enabled=true" \
 #  -e "ELASTIC_PASSWORD=passw0rd" \