ElasticSearch opack: default user and password on new

[nmaguiar]

When creating a new ElasticSearch instance:

var es = new ElasticSearch("http://a.server:9200");

If the aUser and aPassword are not provided it will fail to create. The workaround is to include empty user and password:

var es = new ElasticSearch("http://a.server:9200", "", "");

By default it should consider user and password as empty for ElasticSearch installations that don't have authentication.