NSQ Output plugin

NSQ output plugin, following the NSQ methodology output is a producer
to one instance of NSQD. The go library does not accept array values be
default for a Producer. Additionally service discovery is generally
done as a consumer.

Follows same methodology as Kafka Output without the tag reference.

outputs/nsq/nsq_test.go

@@ -0,0 +1,28 @@
+package nsq
+
+import (
+	"testing"
+
+	"github.com/influxdb/telegraf/testutil"
+	"github.com/stretchr/testify/require"
+)
+
+func TestConnectAndWrite(t *testing.T) {
+	if testing.Short() {
+		t.Skip("Skipping integration test in short mode")
+	}
+
+	server := []string{testutil.GetLocalHost() + ":4150"}
+	n := &NSQ{
+		Server: server,
+		Topic:  "telegraf",
+	}
+
+	// Verify that we can connect to the NSQ daemon
+	err := n.Connect()
+	require.NoError(t, err)
+
+	// Verify that we can successfully write data to the NSQ daemon
+	err = n.Write(testutil.MockBatchPoints())
+	require.NoError(t, err)
+}