Get clickstream demo working with latest ES (v6.6)

Current demo only works with ES v5.6.x, whereas latest ES is v6.6. Would be good to get the demo working with the latest ES.

Previous attempt failed and ran out of time to problem solve.

@rmoff Also did some work and thinks removing the "index": "not_analyzed" may be the trick, but need to test:

PUT /_template/kafkaconnect/
{
  "index_patterns": "*",
  "settings": {
    "number_of_shards": 1,
    "number_of_replicas": 0
  },
  "mappings": {
    "_default_": {
      "dynamic_templates": [
        {
          "dates": {
            "match": "EXTRACT_TS",
            "mapping": {
              "type": "date"
            }
          }
        },
        {
          "non_analysed_string_template": {
            "match": "*",
            "match_mapping_type": "string",
            "mapping": {
              "type": "keyword"
            }
          }
        }
      ]
    }
  }
}