Update janus-gateway/video-room with keepalive

Example wasn't sending keep-alives, causing Janus to eventually
end the session even if we weren't done sending

janus-gateway/README.md

@@ -27,7 +27,7 @@ This example demonstrates how to stream to a Janus video-room using pion-WebRTC
 run `main.go` in `github.com/pions/webrtc/examples/janus-gateway/video-room`
 
 OSX
-```sh 
+```sh
 brew install pkg-config
 https://gstreamer.freedesktop.org/data/pkg/osx/
 

janus-gateway/video-room/main.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"log"
 	"math/rand"
+	"time"
 
 	janus "github.com/notedit/janus-go"
 	"github.com/pions/webrtc"
@@ -99,6 +100,16 @@ func main() {
 		panic(err)
 	}
 
+	go func() {
+		for {
+			if _, keepAliveErr := session.KeepAlive(); err != nil {
+				panic(keepAliveErr)
+			}
+
+			time.Sleep(5 * time.Second)
+		}
+	}()
+
 	go watchHandle(handle)
 
 	_, err = handle.Message(map[string]interface{}{