[CLIENT] Added proper handling of headers in client options to the Ma…

…nticore adapter

The Manticore adapter doesn't handle the `transport_options` in the same way
as the Faraday and Curb adapters.

The addition of a default 'Content-Type' header in 76f8679
(#400) didn't work then, and this patch fixes it.

Related:

    * #400
    * logstash-plugins/logstash-input-elasticsearch#55
    * logstash-plugins/logstash-input-elasticsearch#56

elasticsearch-transport/lib/elasticsearch/transport/transport/http/manticore.rb

@@ -93,6 +93,10 @@ def perform_request(method, path, params={}, body=nil)
           def __build_connections
             @request_options = {}
 
+            if options[:transport_options] && options[:transport_options][:headers]
+              @request_options[:headers] = options[:transport_options][:headers]
+            end
+
             if options.key?(:headers)
               @request_options[:headers] = options[:headers]
             end

elasticsearch-transport/test/unit/transport_manticore_test.rb

@@ -75,6 +75,19 @@ class Elasticsearch::Transport::Transport::HTTP::ManticoreTest < Test::Unit::Tes
         assert_equal response.status, 200
       end
 
+      should "set headers from 'transport_options'" do
+        options = {
+          :transport_options => {
+            :headers => { "Content-Type" => "foo/bar"}
+          }
+        }
+
+        transport = Manticore.new :hosts => [ { :host => 'localhost', :port => 8080 } ], :options => options
+
+        assert_equal('foo/bar', transport.connections.first.connection.instance_variable_get(:@options)[:headers]['Content-Type'])
+        # TODO: Needs to check @request_options
+      end
+
       should "handle HTTP methods" do
         @transport.connections.first.connection.expects(:delete).with('http://127.0.0.1:8080//', {}).returns(stub_everything)
         @transport.connections.first.connection.expects(:head).with('http://127.0.0.1:8080//', {}).returns(stub_everything)