[API] Add list_benchmarks back

Author: estolfo

elasticsearch-api/lib/elasticsearch/api/actions/list_benchmarks.rb

@@ -0,0 +1,27 @@
+module Elasticsearch
+  module API
+    module Actions
+
+      # Return a list of running benchmarks
+      #
+      # @example
+      #
+      #     client.list_benchmarks
+      #
+      # @option arguments [List] :index A comma-separated list of index names; use `_all` or empty string
+      #                                 to perform the operation on all indices
+      # @option arguments [String] :type The name of the document type
+      #
+      # @see http://www.elasticsearch.org/guide/en/elasticsearch/reference/master/search-benchmark.html
+      #
+      def list_benchmarks(arguments={})
+        method = HTTP_GET
+        path   = "_bench"
+        params = {}
+        body   = nil
+
+        perform_request(method, path, params, body).body
+      end
+    end
+  end
+end

elasticsearch-api/spec/elasticsearch/api/actions/list_benchmarks_spec.rb

@@ -0,0 +1,17 @@
+require 'spec_helper'
+
+describe 'client#list_benchmarks' do
+
+  let(:expected_args) do
+    [
+        'GET',
+        '_bench',
+        { },
+        nil
+    ]
+  end
+
+  it 'performs the request' do
+    expect(client_double.list_benchmarks).to eq({})
+  end
+end