Include markdown sample

Fix UI refresh problem
Enable invocation from portal

sample-functions/MarkdownRender/handler.go

@@ -0,0 +1,17 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+
+	"github.com/microcosm-cc/bluemonday"
+	"github.com/russross/blackfriday"
+)
+
+func main() {
+	input, _ := ioutil.ReadAll(os.Stdin)
+	unsafe := blackfriday.MarkdownCommon([]byte(input))
+	html := bluemonday.UGCPolicy().SanitizeBytes(unsafe)
+	fmt.Println(string(html))
+}