Update vendor (slack)

vendor/github.com/nlopes/slack/examples/messages/messages.go

@@ -0,0 +1,32 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/nlopes/slack"
+)
+
+func main() {
+	api := slack.New("YOUR_TOKEN_HERE")
+	params := slack.PostMessageParameters{}
+	attachment := slack.Attachment{
+		Pretext: "some pretext",
+		Text:    "some text",
+		// Uncomment the following part to send a field too
+		/*
+			Fields: []slack.AttachmentField{
+				slack.AttachmentField{
+					Title: "a",
+					Value: "no",
+				},
+			},
+		*/
+	}
+	params.Attachments = []slack.Attachment{attachment}
+	channelID, timestamp, err := api.PostMessage("CHANNEL_ID", "Some text", params)
+	if err != nil {
+		fmt.Printf("%s\n", err)
+		return
+	}
+	fmt.Printf("Message successfully sent to channel %s at %s", channelID, timestamp)
+}