Support Elasticsearch 6.7 & 7.0 docker images

09:58:19.468 [connector-main-0] WARN  com.couchbase.connector.elasticsearch.ElasticsearchHelper - Failed to connect to Elasticsearch. Retrying in 4s09:58:19.468 [connector-main-0] WARN  com.couchbase.connector.elasticsearch.ElasticsearchHelper - Failed to connect to Elasticsearch. Retrying in 4sjava.io.IOException: Unable to parse response body for Response{requestLine=GET / HTTP/1.1, host=http://localhost:33086, response=HTTP/1.1 200 OK} at org.elasticsearch.client.RestHighLevelClient.performRequest(RestHighLevelClient.java:541) ~[elasticsearch-rest-high-level-client-6.3.2.jar:6.3.2] at org.elasticsearch.client.RestHighLevelClient.performRequestAndParseEntity(RestHighLevelClient.java:508) ~[elasticsearch-rest-high-level-client-6.3.2.jar:6.3.2] at org.elasticsearch.client.RestHighLevelClient.info(RestHighLevelClient.java:283) ~[elasticsearch-rest-high-level-client-6.3.2.jar:6.3.2] at com.couchbase.connector.elasticsearch.ElasticsearchHelper.waitForElasticsearchAndRequireVersion(ElasticsearchHelper.java:114) ~[classes/:?] at com.couchbase.connector.elasticsearch.ElasticsearchConnector.run(ElasticsearchConnector.java:136) ~[classes/:?] at com.couchbase.connector.elasticsearch.BasicReplicationTest.lambda$canReplicateTravelSample$3(BasicReplicationTest.java:280) ~[classes/:?] at com.couchbase.connector.cluster.consul.AsyncTask.lambda$new$1(AsyncTask.java:68) ~[classes/:?] at java.lang.Thread.run(Thread.java:748) [?:1.8.0_171]Caused by: org.elasticsearch.common.xcontent.XContentParseException: [15:3] [org.elasticsearch.action.main.MainResponse] failed to parse field [version] at org.elasticsearch.common.xcontent.ObjectParser.parseValue(ObjectParser.java:316) ~[elasticsearch-x-content-6.3.2.jar:6.3.2] at org.elasticsearch.common.xcontent.ObjectParser.parseSub(ObjectParser.java:326) ~[elasticsearch-x-content-6.3.2.jar:6.3.2] at org.elasticsearch.common.xcontent.ObjectParser.parse(ObjectParser.java:168) ~[elasticsearch-x-content-6.3.2.jar:6.3.2] at org.elasticsearch.common.xcontent.ObjectParser.apply(ObjectParser.java:182) ~[elasticsearch-x-content-6.3.2.jar:6.3.2] at org.elasticsearch.action.main.MainResponse.fromXContent(MainResponse.java:150) ~[elasticsearch-6.3.2.jar:6.3.2] at org.elasticsearch.client.RestHighLevelClient.parseEntity(RestHighLevelClient.java:653) ~[elasticsearch-rest-high-level-client-6.3.2.jar:6.3.2] at org.elasticsearch.client.RestHighLevelClient.lambda$performRequestAndParseEntity$2(RestHighLevelClient.java:508) ~[elasticsearch-rest-high-level-client-6.3.2.jar:6.3.2] at org.elasticsearch.client.RestHighLevelClient.performRequest(RestHighLevelClient.java:539) ~[elasticsearch-rest-high-level-client-6.3.2.jar:6.3.2] ... 7 moreCaused by: java.lang.IllegalStateException: unexpected distribution type [docker]; your distribution is broken at org.elasticsearch.Build$Type.fromDisplayName(Build.java:106) ~[elasticsearch-6.3.2.jar:6.3.2] at org.elasticsearch.action.main.MainResponse.lambda$static$4(MainResponse.java:140) ~[elasticsearch-6.3.2.jar:6.3.2] at org.elasticsearch.common.xcontent.ObjectParser.lambda$declareField$1(ObjectParser.java:213) ~[elasticsearch-x-content-6.3.2.jar:6.3.2] at org.elasticsearch.common.xcontent.ObjectParser.parseValue(ObjectParser.java:314) ~[elasticsearch-x-content-6.3.2.jar:6.3.2] at org.elasticsearch.common.xcontent.ObjectParser.parseSub(ObjectParser.java:326) ~[elasticsearch-x-content-6.3.2.jar:6.3.2] at org.elasticsearch.common.xcontent.ObjectParser.parse(ObjectParser.java:168) ~[elasticsearch-x-content-6.3.2.jar:6.3.2] at org.elasticsearch.common.xcontent.ObjectParser.apply(ObjectParser.java:182) ~[elasticsearch-x-content-6.3.2.jar:6.3.2] at org.elasticsearch.action.main.MainResponse.fromXContent(MainResponse.java:150) ~[elasticsearch-6.3.2.jar:6.3.2] at org.elasticsearch.client.RestHighLevelClient.parseEntity(RestHighLevelClient.java:653) ~[elasticsearch-rest-high-level-client-6.3.2.jar:6.3.2] at org.elasticsearch.client.RestHighLevelClient.lambda$performRequestAndParseEntity$2(RestHighLevelClient.java:508) ~[elasticsearch-rest-high-level-client-6.3.2.jar:6.3.2] at org.elasticsearch.client.RestHighLevelClient.performRequest(RestHighLevelClient.java:539) ~[elasticsearch-rest-high-level-client-6.3.2.jar:6.3.2] ... 7 more