[API] Updated the API integration tests submodule to elasticsearch/elasticsearch-rest-api-spec@21bacbb
[TEST] Added support for `skip` within the `setup` expression

A dedicated `skip` expression would be more appropriate for this behaviour:

    skip:
        version:     "0 - 0.90.2"
        reason:      "Suggest is broken on 0.90.2 - see #3246"

    setup:
      - do:
          index:
            index: test
            type:  test
            id:    testing_document
            body:
              body: Amsterdam meetup
      - do:
          indices.refresh: {}

    ---
    "Basic tests for suggest API - pre v1":

      - do:
          suggest:
            body:
              test_suggestion:
                text: "The Amsterdma meetpu"
                term:
                  field: body

      - match: {test_suggestion.0.options.0.text: amsterdam}
      - match: {test_suggestion.1.options.0.text: meetup}

Discussion at elasticsearch/elasticsearch-rest-api-spec@21bacbb